Very Small pontoon Boat Idea

[thetragichippy]

First I would like to say wow......I can't believe I found this forum. I have lurked here for a week reading all the post. You guys are cool. Now, my reason for finding myself here.

I live near a creek (Village Creek, Lumberton, TX) and the water level as well as structures (trees/logs) varies greatly on weather. It is beautiful to canoe and party......or bring the kids. Here is what I want to build. A small pontoon boat that is lite, the platform 5 X12 or 14 feet. Hold at least 4 adults average size with gear. I plan to power it with a couple old trolling motors and perminately mount them in the rear. (probably cutting the shaft. Steer them by cable system (old, old school). Is it possible to build this thing without it weighing thousands of pounds? I found the wooden pontoon free plans and I guess I could make the pontoons longer, but was wanting to get some different ideas. A buddy of mine suggested finding an old Hobie Cat and using the pontoons from that......which sounded pretty good. Any ideas?

[Stumble]

As I read your post I was actually thinking of suggesting buying an old hobie cat and taking off the sail (if you don't want it). It will be a little wider than what you suggested, but they are cheap, easy to find, and spare parts should be a breeze.

The one issue I see is using old trolling motors. Initially it sounds like a good idea. Until you think about the batteries you will need to carry around. Figure 100lbs of batteries for every hour of running time you want. Assuming you use actual Deep Cycle Marine batteries not cheepo car batteries with a different label (you can tell the difference by the weight, the heavier ones are better). My advice is to pick up the smallest outboard you can find (say 2hp). It will be a little more expensive on the front end, but the weight savings and range will more than make up for it.

[thetragichippy]

Thanks for the input. I may have to investigate the trolling motor idea. I was thinking I camp and use my trolling motor a couple days before a charge......but I have 2 batteries and I'm not running them consistantly....so good point. I do have some old johnson 3.5's with gas tank built in. My father had saved about 4 of them in hopes of making one good one. I may have found a use for them.

[Kent Multer]

Hi, I'm not an expert, but my hunch is that 5ft. is too narrow. The boat will be too "tender;" more width will give more stability. Also, it may be a little cramped for 4 adults & gear. As an experiment, you might try drawing a 5 x 12 rectangle on the ground, and put 4 people in there with folding chairs, tackle boxes, cooler, outboard & fuel tank or batteries, etc., and see if it works.

Have Fun! --

[thetragichippy]

Originally Posted by Kent Multer

Hi, I'm not an expert, but my hunch is that 5ft. is too narrow. The boat will be too "tender;" more width will give more stability. Also, it may be a little cramped for 4 adults & gear. As an experiment, you might try drawing a 5 x 12 rectangle on the ground, and put 4 people in there with folding chairs, tackle boxes, cooler, outboard & fuel tank or batteries, etc., and see if it works.

Have Fun! --

You may be right.....but I have to compromise width for practicality. This creek I'm building it for is narrow in spots, but maybe use a 6 ft width....still having issues finding pontoons. I'm also looking at PVC pipes (seen it done on this forum) but I know that is $$$ unless I can find them at an old construction site. So, this may remain a dream until I find the right stuff.

[hoytedow]

In 1970 I built a pontoon boat for 2 adults that was 6 feet wide when assembled. It consisted of 2 - 2 feet wide hulls which were very simple plywood on frames 8 feet long. 2 - 2x4 cross beams held it all together with 3/8 inch bolts and wingnuts and washers for speed and ease of assembly. I carried the whole thing on the roof of my car. It had a 5 HP Sears outboard and a very shallow draft. It was by reason of its beam very stable. I dragged it over logs and such and could go far upriver to places other motor boats could not manage. Motor mount was on the rear cross beam.

[thetragichippy]

Originally Posted by hoytedow

In 1970 I built a pontoon boat for 2 adults that was 6 feet wide when assembled. It consisted of 2 - 2 feet wide hulls which were very simple plywood on frames 8 feet long. 2 - 2x4 cross beams held it all together with 3/8 inch bolts and wingnuts and washers for speed and ease of assembly. I carried the whole thing on the roof of my car. It had a 5 HP Sears outboard and a very shallow draft. It was by reason of its beam very stable. I dragged it over logs and such and could go far upriver to places other motor boats could not manage. Motor mount was on the rear cross beam.

Could you give me a little more info on the pontoons or hulls as you call them? They were 2 ft wide by 8 ft long. How tall were they?

Could I get away with buiding 2 rectangular pontoons 16' long by 2ft wide by 16" tall(deep)? I could use 1/4 in plywood and fiberglass over it.

[hoytedow]

Originally Posted by thetragichippy

Could you give me a little more info on the pontoons or hulls as you call them? They were 2 ft wide by 8 ft long. How tall were they?

Could I get away with buiding 2 rectangular pontoons 16' long by 2ft wide by 16" tall(deep)? I could use 1/4 in plywood and fiberglass over it.

I only built them 12 inches tall but would recommend 15 inches today. I would also recommend for 4 adults that you build them 15 feet long with 3 cross beams, all well braced, 2 bolts at each end of beam with large washers to spread forces over a larger area.. 1 layer of FRP outside.

[thetragichippy]

Originally Posted by hoytedow

I only built them 12 inches tall but would recommend 15 inches today. I would also recommend for 4 adults that you build them 15 feet long with 3 cross beams, all well braced, 2 bolts at each end of beam with large washers to spread forces over a larger area.. 1 layer of FRP outside.

Thanks for the input.

[thetragichippy]

UPDATE: Good news...I think. I found 4 16' pontoons about an hour away for free. Thinking about building the raft(pontoon boat) but using 3 pontoons, having the middle one extended forward. This should allow more weight on deck. The deck will probably be 5X14. First, does this sound like it will work and second, would anyone like to know progress as I build? Finished boat will have small gas motor and steering.

[alan white]

Sounds good. That is, if the pontoons are large enough. What diameter?
I think five feet wide is fine since the bouyancy is at the extreme beam.
Try to use two pontoons if possible. Remember, beaching the boat will always rest evenly on two pontoons, but with three, one will usually have to carry a lot more weight. The beach will be uneven and you might damage a pontoon. Also, the motor will get clean water flow with two.
The idea of a middle pontoon sticking out forward... I'm not crazy about that idea either. If the bow can't stay up the boat's dangerous anyway. Most weight should be a bit aft in any case and a lifeline of some sort should be positioned across aft of the bows.

[thetragichippy]

Originally Posted by alan white

Sounds good. That is, if the pontoons are large enough. What diameter?
I think five feet wide is fine since the bouyancy is at the extreme beam.
Try to use two pontoons if possible. Remember, beaching the boat will always rest evenly on two pontoons, but with three, one will usually have to carry a lot more weight. The beach will be uneven and you might damage a pontoon. Also, the motor will get clean water flow with two.
The idea of a middle pontoon sticking out forward... I'm not crazy about that idea either. If the bow can't stay up the boat's dangerous anyway. Most weight should be a bit aft in any case and a lifeline of some sort should be positioned across aft of the bows.

Man, good points!! I'm glad I am posting ideas and getting feedback. I have not seen them yet but here is the specs of a hobie cat 16:

Length: 16' 7" / 5.04 m
Beam: 7' 11" / 2.41 m
Draft w/ Rudder Up: 10" / 0.25 m
Mast Length: 26' 6" / 8.07 m
Sail Area: 218 ft2 / 20 m2
Weight: 320 lbs / 145 kg
Max Load: 800 lbs / 362 kg
Crew: 1-4
Hull Construction: Fiberglass/Foam Sandwich
Designed by: Hobie Alter & the Hobie Cat Design Team

When I get the pontoons I will measure and post.