Electric Pontoon Boat

Hello!

I'm new to boat design and have been reading this forum about pontoon boats. Some designs included stitch and glue methods, plywood, fiberglass, the use of blue foam, aluminum, and PVC pipe. Learned that aluminum will be expensive and PVC can be fragile and is inefficient/the boat will be very slow.

I would like the pontoon boat to be about 8-10' long and 5-6' wide and holds about 600lbs of weight (we may half only about half that weight on the boat).

I would like to ask firstly: are there any books or guides I should read on boat design? Also, where can I read about calculations that I should know how to do and any guides on doing the calculations?

Next, since this is going to be powered by an electric motor, what would be the best material to use and the best methods of putting it together? I'm looking for efficiency and as much speed as I can possibly get with little power.
What should I expect in terms of budget for the boat without the motor?

Since I am new to boat design, I hope building one will be very doable and not too difficult.

Thanks for all the help!

 

At that size a pontoon is not feasible. Efficiency and maximum speed are mutually exclusive. You need to pick one over the other. There really isn't a best material or method. It depends on the design and your preferences. Make a list of what you want being as specific as possible. That is the SOR (statement of requirements). It will help to answer questions about the boat. For example, is maximum length a constraint?

 

Okay, by efficiency I meant a design such that to minimize backward force from the water, what's the word... drag? So that at it's maximum power the motor can push the boat easily.
Size can be up to 18 feet long and up to 8 feet wide.

If possible, can you explain to me what's feasible? I can't tell what I need until I know what's possible. Any books that you would recommend or sources of learning how to do the calculations for a pontoon to determine what dimensions are possible?

 

Most of the books used are really aimed at sailboat design (the ones that I know).
Skeen's Elements of Yacht Design is one. Others will chime in with their favorite, and may have something more appropriate for your desire.
I'm going to offer two boats which will show you what might be realistic.
First is something I built as a row boat for my wife. 11' long, 5' over all width, each hull is 6" wide. This is only good for ~175# which includes the boat and passenger (maybe 20# more). The hulls only have 4" of freeboard (how far the deck is off the water. It is not going to be good in anything but small waves and will be dangerous with more weight.



You could extend the same hull shape to 16' and carry 300# total.
Both of these will be very efficient - you will get the best speed possible out of the electric motor, but there will be a question of having the right prop for higher speed.
Obviously you will have to make a deck to sit on and mount the motor, which will eat up more of the capacity.

Another option is to make an 11' long, 5' overall, but with 12" wide hulls. This will carry about 350# with 4" of freeboard. This boat will not be so efficient, because the gap between the hulls is not enough, the wave off of each bow will come together between the hulls and slow it down a great deal. I already made that mistake!

Another options is this design. http://www.duckworksbbs.com/plans/gumprecht/cat12/index.htm Not much data shown, but you could probably contact Duckworks to get the capacity and empty weight. This is very narrow overall and will probably have the same problem as I had that a higher speeds with a motor the bow waves will intefere and cause more drag.



Now there is a simpler example:
Take it easy - just a joke

 

Does your 600# weight include boat, motor and batteries, passengers, and stuff? Stuff like fishing gear, anchor, lunch, life vests, etc.

What do you want to do?
Fishing
Sightseeing
Scuba diving
Camping
???

How far do you want to go?

 

Drag is only one thing to consider. This link will give you some idea of what is feasible and what is required to achieve it:
http://www.qis.net/~jmgraham/boatspd.htm
Most of the info is correct, but I am not endorsing their product, this is just a good summary page.

You can start by reading this forum's Efficient electric boats page and asking your questions there:

http://www.boatdesign.net/forums/boat-design/efficient-electric-boat-27996.html

Hope this helps.

PC

 

Defining your needs will tell you what is feasible and what is not. For example, define efficiency? Does it mean that you have one 24 series battery and need to move 600lb for 3 miles? Or, does it mean you have to move 600lb at five knots? As an example, a Hobie Cat 16 is rated for 800lb.

 

Thanks for all the help! At the moment I don't have specific needs, just doing it as a hobby and will have solar panels on it and want to have fun figuring out how to make it as fast as possible with the electric motor that I already have.

The added weight includes mostly the panels, battery, motor, and myself.

 

If you are putting solar panels, calculate the windage and stability if installed overhead. Building a sophisticated hull for maximum performance is hard. If you don't have much experience, a simple V or flat bottom hull will be easier. The other option is to buy a used Hobie Cat without the rig. They are many for sale for less than the material to build a boat. I would say about $300 will get you something in fair shape.

 

Looks alot more complicated than I thought . I guess I may just settle for whatever I can make, efficient or not since I don't have any specific requirements besides doing this for the fun of it. I actually want to build this boat instead of buying one just for experience.

 

First time builders are better off buying plans.
It reduces the amount you have to learn all at once and provides a good base for what you wanted to do.
You might look at the plans from Gary Dierking.
The Ulua would be an easy start, build a deck on the crossarms for extra seating.
I saw something like this without sail and with a tiny motor going out of the yacht harbor in Hawaii in about 1975. I still remember see how easily the guy was going out, along side a sport fisher which was rolling about 30 degrees just in the canal leading out. The outrigger boat was making better time also. The vision has stuck with me all those years.

http://homepages.paradise.net.nz/garyd/

Typical picture https://www.flickr.com/photos/rdkearney/15140443628/

 

Physics are undeniable. The Pinto was famous and infamous. It's rear mounted fuel tank aside, it was famous for getting pretty good MPG (good fuel efficiency) and did so with an anemic engine. Had it a 302 shoe horned into it's engine bay, it would go like a scalded dog, but it's efficiency would also go off a cliff.

The same applies to boats. It's about power verses weight. There are several other factors involved, like hull shape employed and the various forms of resistance, but you don't get something for nothing, so if you want as much speed as practical, you have to pay for this with a power to weight ratio that can provide it. Electric motors follow the same set of physical laws as every other propulsion system, so . . .

 

There is a little more sophistication than small is efficient and big is not.
My Mom had a Pinto MPG which got bad gas mileage - the rear end was such a high ratio (2.0) that when I put a 2.4 ratio rear end in it we got better acceleration and mileage. It was still slow compared to any decent car.

Getting an exact match of all the components counts also. The pinto was just an example. The correct prop on a electric motor that matched the chosen boat could be an improvement.