A better fresh water pump!

How to revive a failing water pump

(and make it better!)

This is a companion blog article to a YouTube video we did on the same topic.

Disclaimer: You must be electrically and mechanically competent to complete these repairs/upgrades.  If you are unsure of any step, stop and get professional assistance.  You can always reach out to me and I will try my best to help.

Our Vision 444 ES catamaran uses two freshwater pumps, one in each hull.  Each one is a 24V diaphragm pump made by Pentair.  Don't worry, the same steps apply to 12V pumps.

We have one in each hull, but we also have crossover valves, which when we open, allows one pump to pressurize the water on both sides.  We normally operate them this way so that we drain water from one tank, then we can switch which pump is powered up and pull from the other tank.

About a year after we launched, the port side pump started acting up.  It would sputter and get sporadic in running as it got close to the cut-off pressure.  It was very obviously sounding different and on it's way out.

I came up with a solution, applied it, and it has been successfully running for about 6 months now, so I wanted to share my solution!

The Problem

Too much is being asked of the little switch that sends current flowing through the pump motor. It's actually a high quality Omron switch, but DC motors suck a lot of current when first turning on, so the contacts in the switch end up arcing as the pump cycles on and off. That's okay, but it does degrade the life of the switch. The switch is rated for only so many electrical cycles (the number of mechanical cycles are rated too, but that takes a looooong time).  When the current is increased, the number of cycles the switch can sustain is reduced.

The Basic Solution

So, the switch fails, you repair it, right?  Yes and no. Okay, yes obviously, but the switch is not made to be or sold by Pentair as a replacement part. You have the replace the entire "Upper Assembly"(94-801-10, which sells for about $60, when the only problem is a $3.50 (or $17 for 4) switch!  

SHURflo AquaKing II - image copyright Pentair

Note, these steps and parts are for the Pentair SHURflo AquaKing II 24V, 5.0 GPM pump (4158-163-A75/E75).  These are likely the same exact steps for the 12V version of this pump and also others in the family that have a lower GPM rating.  Reach out if you are not sure!

Replacing Just The Switch

Parts

So, if you want to replace the switch by itself, you will need the following:

• New Switch - Omron - V15-2C26-K (Check yours first)
• Soldering Iron
• Solder
• Rosin soldering flux (highly recommended)
• Screwdriver (Phillips)
• Optional
• You may need some crimp connecters to re-install the pump to your boat.
• We try to keep a spare of just about everything.  Not a bad idea to have an upper housing spare on the boat anyways, and if this repair goes sideways, or you loose a part, you will still be able to repair the pump using that!

These are the three screws that hold on the switch housing

Steps

1. Remove the pump from the boat
1. Un-power the pump (switch, breaker or fuse, depending on your boat)
2. Drain water/pressure from your freshwater system by opening a low water outlet (sink, shower, etc).  Leave this open while you work.
3. Remove the water connection
4. Remove the electrical connection (this may require cutting wires)
5. Place the pump where you can work on it and don't mind some residual water draining.
6. Remove the three Phillips screws that are holding on a small cover on the Upper Assembly.
1. There are quite a few parts inside that will fall out. They are easy to re-install, just don't loose them!
2. One screw is longer and goes through a longer section of the cover you are removing.
7. Carefully work the switch out of the plastic housing.
8. When out, work the rubber insulation boot about 6 inches down the insulated wire.
9. Remove the slide-on connector from one of the switch contacts.
10. Unsolder the wire from the remaining switch connector.
11. While the wire is hot, re-solder this wire onto the equivalent contact on your replacement switch.
1. Flux and a high wattage iron will help a lot. Be careful not to touch anything with the tip of the hot iron and have a safe place to reset it when not using it!
2. Turn off your iron when done and place it somewhere safe to cool.
12. Slide the other connecter onto the new switch.
13. Slide the rubber boot down the wires and up against the switch.
14. Slide the switch and rubber boot back into the housing.
    (There are rails and grooves that mate with one-another).
15. Re-assemble the switch and cover to the pump upper housing.
1. Make sure the beige rubber plug is fitted flush into the pump upper housing.
2. Place the three screws through the switch housing.
   Make sure the long screw goes through the thickest portion of plastic.
3. Place the small, round plastic plug (shaped like a top-hat) into the switch housing hole, on to the top of the adjusting set screw.  The skinner button portion of the plug should face out.
4. Insert the pressure spring into the same housing hole.
5. Place the gasket onto the screws, aligning the shape of the gasket to match.
6. Place the black plastic lever into the intermediate plastic piece.
   It can only fit one way.  The bump on one end of the lever will align with the button on the switch.
7. Carefully slide the intermediate piece and lever onto the screws of the switch housing and gently squeeze together. You would be able to manually activate the switch using the part of the lever that will mate with the beige rubber plug.
8. Make sure that everything seems to fit together well.  
9. Place this against the pump housing and carefully screw in all three screws, while holding the pieces tightly together (so nothing can more out of place).
10. Snug the three screws with modest pressuse- they are just in plastic.
16. Reinstall the pump into the boat, connecting the water connections, electrical connection and tightening the mounting screws.  
17. Apply power to the pump.  It should start to operate, and since you have a tap open, you will be able to work the air out of the system.  Do not close the tap until you expel the air pocket that was introduced.
18. When you close the tap, the pump should run for no more than 10-20 seconds, build pressure and turn off.  If it does not, open again and make sure there is no more air in the system.
19. If it still does not turn off, you may need to adjust the pressure cut-off set screw with a 2mm allen wrench.
    If you need to loosen this screw by more than half a turn, something else is wrong, recheck everything and if no luck, reach out to me!
20. Double check that your water connections are not leaking and that there are no leaks around the switch housing.  If there are, snug those three screws a little more.
21. DONE!

Check out the YouTube video to see how bad our old switch looked internally!

The Advanced Solution

Why You Need It

The advanced solution is highly recommended if you are a live-aboard, or just want a more robust solution that will likely never require another switch replacement.

Unless you pump is lightly used, I would suggest starting by replacing the switch, as detailed above. 

The proper solution, is to allow that small micro-switch to operate within its designed parameters. In order to do that, we will have to insert another device which handles the high current, while the micro-switch simply tells this device when to turn on.

How To Accomplish This

Some of you are probably thinking relay! Yes, it is a relay, but a specialized type of relay.  Relays, at least electro-mechanical relays, ultimately have the same contact arrangement as the micro-switch, just larger and hopefully better able to handle the motor current.  It will take a lot longer, but they will succumb to the same contact erosion and eventual failure.

The solution I prefer is to use a Solid State Relay (SSR for short).  From the outside, these work just like the electro-mechanical versions, however internally, they are quite different.  The current switching is being done by a semiconductor called a MOSFET (Metal Oxide Semiconductor, Field Effect Transistor).  Apply a small charge to the "gate" of the MOSFET and the PN junction will then "open" and allow electrons to flow.  This is really the basis of how every semiconductor works.

E-T-A Solid State Relay - image copyright E-T-A

At any rate, when the electrons are allowed to flow, they are not having to jump across any tiny air-gap, so there is no arc, therefore there is no erosion taking place and the MOSFET will survive indefinitely, as long as the maximum amount of current does not exceed it's rating (which has to do with channel width in the silicon).

TLDR - A properly sized SSR can be switched by an incredible small current from the micro-switch and allow the large motor current to flow without sustaining damage!

Adding in an SSR

Parts

In order to perform this upgrade, you will need the following:

• SSR - This will vary based on the voltage and fuse fating (as shown on motor) of the pump you have.
• 24V, up to 10A Pump Fuse Rating - E-T-A ESR10-NC2A4HB-00-D2-10A - $19
• 12V, up to 10A Pump Fuse Rating - E-T-A ESR10-NC2A4HB-00-D1-10A - $26
• 12V, up to 17A Pump Fuse Rating - E-T-A ESR10-NC2A4HB-00-D1-17A - $36
• Wire cutters
• Wire stripper
• Wire connector crimper
• Female, 0.187" crimp quick-connect insulated connectors for small tabs on SSR.
• 14-16 gauge - one for wire from micro switch - TE Connectivity 3-350816-2 - $0.30
• 18-22 gauge - one for added wire from power - TE Connectivity 2-520181-2 - $0.30
• Female, 0.25" crimp quick-connect insulated connectors for large tabs on SSR.
• Sized for the wire on your pump, you will need two each
• 10-12 gauge - TE Connectivity 4-520448-2 - $0.35
• 14-16 gauge - TE Connectivity 3-520141-2 - $0.40
• 6" Length of marine wire, Red, 12 or 14 gauge (to match the red wire gauge on your pump)
• 6" Length of marine wire, Black, 18 - 22 gauge (carries almost no current)
• Soldering Iron
• Solder
• Soldering flux
• Two 1" long pieces of heat-shrink tubing, large enough to slide over two pieces of pump motor wires laid on top of each other.
• Lighter or heat gun to shrink heat-shrink tubing.
• 6-8" piece of electrical tape
• Optional
  I'm a big fan on using these same Quick Connectors when you re-install the pump into your boat.  It is so much easier to take the pump out to replace any items, and if you use Quick Connect connectors, this becomes so much easier.
• Female, 0.25" crimp insulated connectors for boat side of your pump connection.
  (same as above) - Choose the size that matches your boat wiring.
• 10-12 gauge - TE Connectivity 4-520448-2 - $0.35
• 14-16 gauge - TE Connectivity 3-520141-2 - $0.40
• Male, 0.25" crimp insulated connectors for pump side of pump connection.
  Choose the size that matches your pump wiring.
• 10-12 gauge - TE Connectivity 4-521098-2 - $0.70
• 14-16 gauge - TE Connectivity 3-520107-2 - $0.65
• You may also need some nylon ties (Zip-Ties) to tidy up your re-installation.

Diagrams

Okay, a couple pictures, will hopefully make this make better sense.

First, this is how the pump normally works in your system:

Standard Water Pump Configuration

Preparing Water Pump for SSR

SSR Water Pump Configuration

The quick description of the process is that we cut the wire coming from the switch to the motor and insert the SSR so that high current flows from the boat, through the switch portion of the SSR and into the motor.  The control side of the SSR is powered by the signal coming from the small switch inside the pump housing and we also provide a return path for that switch current back to the boat negative.

Steps

1. Remove the pump from wherever is is mounted, following steps 1 through 5, above.
2. Cut the red wire that goes from the switch to the pump motor, about in the middle.
1. Strip about 3/16"-1/4" of insulation from the end and crimp a 0.187" tab, female quick- connect connector to the wire coming from the switch.
2. Strip about 3/16"-1/4" of insulation from the end and crimp a 0.25" tab, female, quick- connect connector to the wire going to the motor
3. Create a gap in the insulation on the main red and black wires that used to be connected to your boat, as follows: *See below for a tip on how to do this
1. Red wire that is going to the switch, place the gap at about the same length from the switch as where the other red wire was cut.
2. Black wire that is going to the motor, place the gap so that it will be close to the opening in the red wire however the pump was mounted and wire strung in your boat.
4. Take the 6" length of red wire, strip one end about 1/2" and wrap around the exposed conductor in the gap of the red wire.  It should make at least one full revolution.
1. Solder this connection, making sure the added wire cannot "spin" around the original wire when complete.
2. Slide heat shrink over this connection and carefully apply heat to shrink onto wire.
5. Take the 6" length of black wire, strip on end about 1/2" and wrap around the exposed conductor in the gap of the black wire.  It should make at least one full revolution.
1. Solder this connection, making sure the added wire cannot "spin" around the original wire when complete.
2. Slide heat shrink over this connection and carefully apply heat to shrink onto wire.
6. Cut the 6" wires shorter, if desired.  This will allow the SSR to be connected in, without excess wire length.
1. Strip about 3/16"-1/4" of insulation from the end of the red wire and crimp a 0.25" tab -female quick-connect connector to this wire.
2. Strip about 3/16"-1/4" of insulation from the end of the black wire and crimp a 0.187" tab female quick-connect connector to this wire. 
7. Attach the four wires as follows:
1. Small (0.187") connector on the red wire to pin 1.
2. Small (0.187") connector on added black wire to pin 2.
3. Larger (0.25") connector on added red wire to pin 3.
4. Larger (0.25") connector on red wire going to motor to pin 5.
8. Wrap a few loops of electrical tape around the bottom of the relay and the connectors to secure and insulate everything.
9. Optional: As mentioned above, I'm a big fan of adding these same style connectors to the wiring connection between the boat and the pump.  If you want to do that:
1. Strip the end of the red and black wires on the pump and the boat by 3/16" - 1/4".
2. Crimp FEMALE quick-connect connectors to the red and black BOAT wires.
3. Crimp MALE quick-connect connector to the red and black PUMP wires.
10. Re-install the pump into the boat, following steps 16 to 20 above.
11. Once you are happy with everything, consider using a nylon tie to secure the relay and wires into a nice tidy bundle adjacent to the motor of the pump.

Pin Assignment for SSR

Pin assignment from E-T-A Datasheet - copyright E-T-A

That's a Wrap!

Whether you use your boat on the weekend or live-aboard full-time, you want to be on your boat enjoying yourself, not doing unexpected work.

To me this is a perfect example of investing a little time and expense on your terms so that your enjoyment is ruined (usually at the worst possible time - I think that should be called Neptune's Law) 

I hope you enjoy this tutorial and it all made sense and was easy to follow. If not, please take a moment to let me know via comment so I can fix it.

Also, please leave a comment if you put this into place and tell me how things went!

Mira - Network Diagram

 A few people have asked for more details about out network on-board.  Instead of trying to describe it, and because I should have one anyways, I decided to create a Network Diagram.

So far, the network has been working great.  On occasion, the 2.4 GHZ radio in the MNC-1250 stops responding, however I am working with their tech support to get to the bottom of it.  We have that device mounted upside down to the "ceiling" of what I call the network area in the owners cabin.  I have a suspicion that it maty be overheating as it it not sitting in the orientation it was designed to be in. 

As it turns out, I have a spare 12v computer-type fan that I am going to wire into the 12V fuse block in there and mount it to the router and see if that makes a difference.  I also went into the configuration settings and turned down the output power of both the 2.4GHz and 5GHz radios, since the signals do not have to go very far to cover the boat.  This should also reduce the amount of heat generated.

Have a look at the diagram and let me know if you have any questions!

SV Mira Network Diagram

Using a NAS (Network Attached Storage) device on a boat as your own personal Cloud.

Living on a self-sufficient boat

without giving up The Cloud?!

If you are at all like me, you've begun to rely more and more on one or more Cloud Services.  Apple iCloud, Dropbox, Google Drive, Microsoft OneDrive and many, many more basically all offer the same solution:

"You have digital things that are important to you; you pay us a small amount per month and we'll manage keeping it safe and protect you from hardware failures and data loss."

I firmly believe that hosted cloud storage is one of the great conveniences that just about anyone under the age of 70 should be using.  The solutions are downright cheap, given how much storage capacity you can get and how much you would pay to get that data back if you lost it.

I have used all of the above and my provider of choice is Google Drive, though we also use Apple iCloud to automatically backup our iDevices, as least for now.

Life 2.0

We will still have a cloud storage provider when we set sail, but what are we going to do to maintain the security of data and content we create while we are away from internet connectivity and can't sync to the cloud?  We are gong to be capturing pictures and video, notes, maintenance logs, etc., etc., and we won't want to risk losing it.

We also have a lot of CDs and Movies that we want to have access to, but can't afford the physical volume consumed by the discs.  We could use one or more external hard drives and plug them into a laptop when we need that slightly more stable hard drive that doesn't get used as much, but that comes with a bunch of restrictions, like multiple users at one time and the inconvenience of trying to play music or video to a TV from a USB hard drive.  Some TVs will do it, but usually the interface is clunky at best.

NAS is the Answer!

The answer is NAS and if you haven't used one since the early Western Digital days, boy have they come a long way!  I began researching this this fall and quickly decided that the Synology line of NAS seemed to offer what I needed.  Multi-bay devices using an Intel Processor, one or more LAN ports and running some version of Linux for management.  They offered file storage, SMB for mapping network drives, and at least form of Media Server.  Perfect! Just what I was looking for.

NAS Choice

I decided on the Synology DS220+, which was right at $300 delivered.  Synology seems to be a (the?) market leader for high quality Network Attached Storage box solutions.  It is a dual bay, dual LAN port, high-end consumer / low-end business model that seemed to be the right trade-off between price and capabilities.  Power consumption of the box itself is relatively low at 4W (from 12V wall wort adapter, which I hope to remove and tie directly to a fused 12V) when the drives aren't doing anything.  Not too mention, the entire unit can be scheduled to turn off and back on at pre-determined times, allowing the actual power consumption to fall even lower.

It comes bare, meaning, you get to decide on the storage type and capacity that's right for your use-case.  While they have 4, 5 and higher count bay models that also support higher RAID levels, this really just increases performance, and with no more than 4 users at a time and usually just 1 or 2 users, that would be overkill.

Drive Type

Power consumption and ruggedness are the two most important considerations for use on a boat.  That quickly led me down the SSD (Solid State Drive) route.  Unlike traditional, rotational Hard Drives, they have no moving parts, consume less power and can take a lot of G forces before failing.  Vibrations that would kill a rotational HDD are of little concern to a SSD.  Perfect for boat use! 

The SSD we chose is speced at 4W of power consumption, max and close to zero when idle.  A rotational HDD can get close to zero if in standby mode, but will take a second or two to spin up (and consume 10Ws for a short period), and then consume about 3W just spinning and up to about 8W when accessing data. 

SSDs are very fast at accessing data, almost twice that of HDDs, but that really wont factor in for our uses. 

Unfortunately, SSDs are WAY more expensive than rotational drives, AND they have a limited number of writes that can be performed before the NAND FLASH can no longer be trusted to remember the data stored, but given that I can't run to a floating Best Buy or Amazon Prime a new drive the next day, SSD was the obvious choice because of their ruggedness and reduced power consumption. Oh, and while the number of writes is "limited", it's limited to 2,400,000 GB of total data written for the 4TB drive we purchased, so that is completely filling and emptying that 4TB drive 600 times.

Drive Choice

We opted for the Samsung 870 EVO SSD.  This technology is a good blend of reliability and price point.  The plan was to use 1 drive; more on that latter.  It uses technology that allows three "states" to be held by each NAND cell.  Original NAND cells could hold two values, either a one or zero.  There are also quad cells that can store 4 "states" per cell.  The more states per cell, the less silicon real estate is needed and the price drops, BUT, the more states per cell, the less reliable and the fewer writes that can be trusted.

Now comes capacity.  What would we need? How much would be consumed by music CDs and Movies?  How much would we expect to create and need ready access to? NO IDEA!  So, given the afore mentioned lack of floating Best Buys, we decided to get a large drive; 4TB to be exact.

As of the writing of this post, they run about $470.  To give you an idea, a regular HDD in that capacity costs about $70.  And, if we had opted for the PRO version of the SSD (860 PRO, dual value per cell), it would have cost just under $995.

The exact Drive we purchased can be found here:  Samsung 860 EVO 4TB
Need less space?  They also make a 2TB version (Samsung 860 EVO 2TB) and a 1TB version (Samsung 860 EVO 1TB) at the same cost per GB which are viable options.  There is a hefty price premium on the smaller 500GB and 250GB versions so I personally wouldn't bother.

We have 340 CDs and 174 movies stored so far and we are using about 700GB, so 20%.  2TB probably would have been just fine, and 1TB might have been fine with less movies (they take 1-2 GB for a DVD and up to 17GB for a Blu-Ray).  Given that we will be producing our own YouTube videos (about 5-10GB each with raw footage), I'm glad we opted for 4TB.  Plus, the less capacity we use, the longer it takes to reach the Total Data Written limit (end of life) of the drive.

Lesson Learned

Solid State Drives are known for being exceptionally reliable.  HOWEVER, Murphy and his law can affect them just the same.  About 3 months after using the NAS, I suddenly started getting S.M.A.R.T. errors, which is an acronym for a self test that has been built into all drives for quick a while.  It is meant to let you know that a drive is experiencing a problem and that a backup should be made and the drive replaced.  I dug into the errors and sure enough, the drive was having some pretty severe failures and they were becoming more frequent, quickly.

At this point I had transferred about 15GB of photos, 56GB of music (340 CDs) and 600 GB of movies (174 movies) and didn't want to go through that ripping process again. Fortunately we had not taken the CDs, DVDs and Blu-Rays to the dump yet, so it was recoverable if we lost everything.

This was a very fortunate experience in a lot of ways.  It reminded me that "more reliable" is still not necessary all that reliable.  Early-life-failures happen with electronics, even though these drives have a very strong 5 year warranty.  I was positive that Samsung would replace the drive because of that strong warranty.

It made me realize that I really need to have a dual drive solution, especially since the NAS supports it.  This would allow redundancy and the chance of two drives failing at nearly the same time is incredibly low, especially in early life.  If one drive fails in the future, well then I likely would either backup to a rotational (cheap drive) and keep using the NAS until I can get a replacement, or I'd just turn off the NAS and live without it until I could get another drive, to have the best security of preserving the data.

The downside is the exceptional cost (investment?) of ANOTHER 4TB SSD.

Setup

The bare drive had to be loaded into the NAS, which involved setting the four included screws into the carrier included for each of the two possible drive bays, then sliding it in to the NAS bay until it clicks.  Plug in power, and at least one ethernet cable and you are ready to turn it on with the button on the front.

By default, it will get an automatically assigned IP address from your router.  I eventually set my router to always assign the same IP address to it to make it easier to find (10.0.0.10), and you can also give it a memorable name in the configuration so that you can just type that into a browser address bar to connect.

Configuration and Management is done from a windowed environment and will look similar to this:

Most settings are found under the Control Panel and data can be accessed under File Station, however the part I really didn't appreciate is how extensible it is with a huge list of add-on packages that can be Installed; all supported and/or vetted by Synology.

Capabilities and Services

This isn't meant to be a deep dive article in how to set-up and configure, but let me list out the services that exist AND that we will use on the boat. (There are many more; a lot of them aimed at business users.)

• Media Server - Our Music, Video and Photos can be streamed from the NAS to just about any device (computer, smart TV, tablet, phone, our marine radio)
• iTunes Server - Stream content as if it is being streamed from a computer based library
• Plex Server - Super fancy way to present and stream your library if you are connecting from a device that has a Plex client (phone, tablet, probably some TVs, etc.)
• Personal Cloud - We will be able to use our NAS device as a Google Drive type appliance.  We will have a remote shared drive on the NAS that we will both attach to from our computers and tablets and access it just like Google Drive.
• Auto-Cloud Sync - When we DO get access to data, the NAS will notice that, and start syncing any changes of data since the last time (it can also be a subset of the data; maybe everything but movies, for example) up to our Google Drive account.  Basically the NAS acts as a robust holdover until we get access to the actual Cloud.
• Media Wiki-server - Ever use Wikipedia?  Ever edit or write an article using a Wiki?  If not, it's super easy and a Wiki is a great repository for things like digital manuals, instructions, log of places visited, maintenance log, etc.  Some of these need to exist on paper too, but having a digital copy is gravy.  Not too mention, being able to use my tablet to pull up a manual in the engine compartment and being able to text search, zoom in, etc.!
  
  
  

  

  Mira Wiki

  
  
• Calendar Server - We will be able to both connect to one shared calendar on our phones, tablets and computers, just like we do now.  Instead of that calendar data residing on a Google Account, it will reside on our NAS.
• Contacts Server - Same as above, but for contacts.
• Chat Server - This one seemed unlikely to be used until I thought about it.  I'm at the helm and Sue is down in the cabin taking a nap.  I need her help soon and want to get her, but don't really want to leave the helm.  I can text her and she will get an alert on her phone on the Synology Chat app, using the NAS as the chat server.  Have a guest on board? They can be added super easily.

Upgrade

Since I plan on using so many of those services, I opted to upgrade the internal 2GB memory with a 4GB SODIMM (like a laptop) stick to top it out at the supported 6GB of RAM (though there are a lot of users out there running much more).   Synology sells a "supported" memory stick at a hefty price.  You can find it here for $89. 

From my reading, if you have a problem with the NAS and have un-supported memory installed, they will not support you,...until you remove the added memory stick.  Plus, memory is memory (if a reputable brand).

I opted to get the Samsung version of the same thing for $17. 

Could we have gotten by without it?  Probably, but $17 and no floating Best Buy.

Installation is super easy.  Power off the NAS, remove the right most drive/empty carrier.  The memory slot if easily visible and can be easily popped in.  Replace the drive/carrier, power it back up and you are set; nothing else to do.

Summary

I only expected to get about 4 of those features listed above, but as I learned more of the capabilities, I quickly realized that this device would easily be able to be our "cloud" on the high seas and believe it will become a focal point of our data and entertainment management on-board.  4 watts of continuous draw going up to 8-10W during use is not trivial, so you may want to do some power management and turn it off when not using it, or schedule it to only be on during normal use times.  With 3000W of solar, and a huge bank of Lithium-Ion I think we will be able to keep it up and running most of the time, but we can adapt as needed.

Lastly, I'm also glad I began this process early; it is so much easier with true broadband and it also allows me to test out the approach and allowed me to find that early-life-failure of the SSD.

Thoughts?  Questions?  Let me know in the comments below!

Disclaimer: As an Amazon Associate I earn from qualifying purchases.  I will only include links to products with which I have had direct, positive experiences.

Tech Article - Hull Speed, Displacement Boats and Planing Boats

Tech Article posts are those that came about because of something I was writing in a more typical blog entry and decided to break out as a reference item.

Hull speed is nautical speak for maximum theoretical speed for a "displacement" boat.

A boat is basically just plopped into a body of water and displaces an amount of water equal to the weight of the boat.  A boat's weight and it's displacement are the same. 

That is true for every boat that is not moving.

Once you add movement, that can change.

A displacement hull is the name used to signify a boat design where the hull just pushes water as the boat moves. The fastest a displacement hull boat can move (Hull Speed) is determined with the formula:

HS = 1.34 * SQRT(LWL)

HS is the Hull Speed in Nautical Miles per Hour, aka knots 

LWL is the Length at the Water Line in ft.

As an example, as 38' monuhull sailboat, may have a 33' LWL.  Therefore, the Hull Speed for this boat will be:

HS = 1.34 * SQRT(33) = 1.34 * 5.74 = 7.7 knts

A Nautical Mile is a little longer than a regular (statute) mile, so 7.7 knts = 8.85mph.

That is the fastest that boat can move, (*kind of, more on that later). 

You may wonder why and the answer is kind of neat.

When a boat is moving through the water, it is moving that water and creating a wave of its own.  That wave starts at the bow (the very front) of the boat and rises up highest at the bow.  From the bow back, the height of the wave falls off and then starts to rise again, like any other wave in a body of water.  When a displacement boat is moving very slowly, there is a wave that starts at the bow and then falls off quickly.  As the boat accelerates, the wave takes longer to fall off, until eventually, it falls off and rises again at a distance that is equal to the boats length at the waterline.  The boat is trapped in the trough of its own wave and has reached Hull Speed!

Taken from a post on Cruiser's Forum

So to become un-trapped, the boat will have to exert considerably more effort so that it can push up against the front of that wave and start to ride on top of it.  If the boat has the power to do that, the boat is now said to be planing, where it is riding on top of the water instead of just sitting in it.  Hull design can make this a lot easier, and while the effort to go into planing is substantial, once the boat is there on top of the water, it doesn't take as much effort to stay there.

That's why a shorter bass boat, which may only have an LWL of 28', can reach a top speed around 60 mph.  At 28' long, it is only operating as a displacement boat until it hits 8mph, at which point and when given enough added horsepower, it becomes a planing boat.

It's also why a 1000' long oil tanker, weighing almost 1 million tons can travel much faster than a relatively light (8 ton) sailboat.

* so I said "kind of" earlier, referring to the maximum speed of the hypothetical 38' sailboat and that's "the fastest that boat can move".  If you add enough power, any hull will become a planing hull, but in reality, you never would and probably never could add enough to a regular sailboat to get it to be truly on plane.