Hatching a glass-bottomed plan

So, you folks might remember my S.A.F.T. acquisition of a few months' past:

Exhibit A.



I was planning on using these to power the moped conversion, but their 80lb weight scared me off.

I had the opportunity to drive an aluminum fishing boat (14 feet long) with a Minn Kota 12v trolling motor last weekend - the cheapest model made. 30lbs nominal thrust... and after 40mins of running the power leads from the battery to the motor melted, with smoke spewing from the switch housing!

Exhibit B.



I'm ready to attribute the failure to a poor switch, as the leads from the switch to the motor did not suffer any damage.

Now, there are 24V versions, sporting 80lbs of thrust - much more my speed - but this is one option of many under consideration.

Here comes the fun part: my dad, a former composites business entrepreneur, has stashed away a stock of 4mm "hardcoat" Lexan in 4x8 sheets... which I have permission to use!

I intend to build a small electric boat with a section of glass bottom - using these batteries, the Lexan, and I'm not sure what else. I have an eTek and Alltrax 4834 at my disposal, but a ready-built trolling motor might fit the bill nicely..

So - the design criteria.

1. Must be able to run in shallow water, weedlessly.

2. Must be able to float 4 passengers and gear, to a gross payload of let's say 500lbs.

3. Must be able to be dragged along shores without damage. (a wood hull is out)

4. Must be able to handle 18 inch waves.

5. Maximum length 18 feet, max width 6 feet..

6. Needs a cloth canopy to provide shade.

This is intended for weekend sight-seeing on a sheltered lake with exceptionally clear water... speed is not a major concern, nor efficiency - If the 24V / 27Ah pack can get me an hour or two on the water, I'm happy.

I'd like a window in the bottom that two people can look through at the same time.. a few feet square at least.

What do you think, folks?

18 foot waves? Even if you're not measuring them the way we do in Hawaii, that is a huge wave for a little boat, especially if you are anywhere near the shore when they might start breaking. If you are on a sheltered lake, why does the boat need to be able to handle 18 foot waves?

Wait, I just noticed, did you get the ' and " mixed up on #s 4 and 5? Is it supposed to be 18 inch waves and 18 feet long by 6 feet wide, rather then 18 foot waves with a boat 18 inches long and 6 inches wide?

Cool idea! A sheltered lake has 18' waves? Or 18"? Can't remember the name but there are some really nice high powered trolling motors made and some folks using a small outboard lower unit and fitting an electric motor to it. A search on the site should find it. There is at least one thread about electric boats here with a bunch of links.http://endless-sphere.com/forums/viewtopic.php?f=39&t=9806&p=290643&hilit=electric+boat#p290643 i think this is it. Maybe put some lights on the bottom too so you can see even deeper.. :lol:

northernmike said:

I had the opportunity to drive an aluminum fishing boat (14 feet long) with a Minn Kota 12v trolling motor last weekend - the cheapest model made. 30lbs nominal thrust... and after 40mins of running the power leads from the battery to the motor melted, with smoke spewing from the switch housing!

Click to expand...

I have that same motor. Was going to put it on my Kayak. So the motor worked on 24V except for the cables? Did you run all speeds? I was curious how the speeds are implemented. Somehow by tapping into different wirings on the motor I read. (There is supposedily no electronic speed control) Then I was wondering if the lowest speed is simply running the motor with a higher count wirings, then I should be able to run the motor on a higher voltage using that wiring and get the same effect as a higher speed on lower voltage.

Example: Say high speed is 8 turn and low speed is 16, then running 16 turns at 24V should be same as 8 turns at 12 V. If I'm really lucky the lowest speed should be runnable at 48V, my ebike battery is 48V, and I simply need to add an inexpensive controller to vary the speed.

The cheap Minkota motors have what they call 'speed coils' which are really just big resistors. They switch these in series with the motor to control speed; crude and wasteful of power. The maximum power connection is a direct feed to the motor though, so you can just use that and hook it up to a brushed motor speed controller. You get much better efficiency by doing this, as I pointed out in the other thread.

Jeremy

Sorry, used to metric here in Canada... trying to make it easier for the bulk of readers I goofed!

I was running the Minn Kota on 12v at the time, I have not tried it with higher voltages.

On this little motor, the direct connection to the motor Jeremy's pointed out are a pair of 14 gauge wires.. not too inspiring.

If I could afford it, I'd love a Torqueedo for this project. There are some great videos of them powering small planing hulls, so performance wise, I'm impressed. It is somewhat off-putting to me that they look so much like the Gardena brand garden tools their designer also penned.. I mean, they're nice garden tools, but this is a MOTOR!

Here's some inspiration:

Lexan canoe:



Bear Mountain Boats' new solar / battery / diesel genset backup all-wood launch, launched very recently:

Hmmn. I'm really enjoying the form of these, but I'd like something with more relaxed seating and a little more room.

Oh, wow, look at these...

Those last ones look like wood hulls. Just about every region with sea coast or lakes will have a local boat building tradition. Not long ago being able to build a simple row boat for everyday use was a skill many had. Today joining a club where they preserve these traditions is a great way to learn some great woodworking skills, meet likeminded, step out of todays TV and McDonalds culture, and relax in good company.

A boat like this is not hard to build:


An upgrade is a slightly more refined round bottomed:


With some good woodworking skills and patience one can also build "kravell", where the boards mate precicel;y against each other (as opposed to "klink" where there is a fporgiving overlap -- sorry don't know if these words translate same in English) Kravell (Caravell (s)?) lends to some very refine and lightweight hulls.

I'm coming to realize, I might have to build this out of wood after all. Perhaps I can coat the bottom in something suitably durable... any suggestions?

Glen-L has some great designs:

Here's their 9 foot glass bottom - the center section is a little "viewing cone", provides shade to the glass to eliminate glare I suppose..





What they call the "Lo-Voltage":



Their "Amp Eater" (perhaps a bit too small) :

Have you considered a HobieCat/HobbyCat as a platform. Nice light, stable easy to propel vessel. Just make a pair of viewing boxes that slide down in frames. "Glass" bottom boats are a total pain in the ass as the surface will always get scratched. A viewing box is far easier to protect, build and replace.
JWITIK

Sorry Gordo, thanks for the ideas but I'm really looking for a monohull design. I have a boathouse already for the purpose, a wide catamaran sailboat is totally out of the question.

Another that has caught my attention today:



19 foot Elco

northernmike said:

Sorry Gordo, thanks for the ideas but I'm really looking for a monohull design. I have a boathouse already for the purpose, a wide catamaran sailboat is totally out of the question.

Another that has caught my attention today:

19 foot Elco

Click to expand...

Haha Good pic. It looks like the "groceries" are already on the dock I think maybe Gordo meant the smaller Hobiecat .. They do make some pretty small. It would be a lot easier and probably cheaper to mod an existing hull. Plus it will give you ideas for the 2nd version. There's always a second version, right?

Here is a couple. A 10 and 12 footer.

Really???? Wow, I had no idea, and that REALLY added to the topic.