Help me design a pontoon vessel

[Macamato]

My Bride & I are planning a trip down the Ohio and up the Mississippi late next summer and fall to celebrate our 50 years together.

We have a Sunlite Eagle fold down slide in pickup camper that we want to mount on a pontoon vessel to use to take this trip. It weighs less than 2,000# loaded with food, fuel, water and clothing.

We have purchased two 25" x 24' aluminium pontoons and a trailer to haul it.

We have access to two 25 HP Mercury 2 cycle outboards that we are hoping to mount for propulsion.

The rest of the design is in a high state of flux at this time.

Therefore, any suggertions will be greatly appreciated.

We hope to use mostly native hardwood for the structure. We have access to most any species and also have a solar powered kiln. Our plans are to use a combination of white oak and red elm. The white oak for rot resistance and the red elm for toughness. We also have access to aeromatic red cedar but really dont anticipate any uses for it at this time other than maybe inside the comand center.

We are seriously looking at 3/4" treated plywood for the deck.

We would like to mount the two outboards between the pontoons to help protect them during locking operations etc. Any designs of how to accomplish this would be appreciated.

We are planning on making a weather proof comand center with a plexiglass windshield. It will also be insect proof but ealily converted to open air mode. This we will work on in our woodworking shop this winter.

I am concerned about the speed and shift controls for the twin Mercury outboards. Is is difficult to get them sycnronized? Are there commercially manufactured controls for accomplishing this?

We are thinking of having an old fashioned spoke wheel for control. I am thinking of making it in my workshop. Would this be adequate to control the vessel using aircraft cable and pulleys?

We are thinking of mounting it in the center of the comand center between the two seats so that is can be controlled from either seat.

As you can tell, there are lots of problems yet to be solved. My reason for posting this lengthy item is to hopefully avoid any bad experiences that others may have had while attempting something such as we are committed to.

Sincerely
Macamato

 

[Silvertip]

Re: Help me design a pontoon vessel

My suggestion would be to scrap the plans for the following:

Two outboards on a pontoon are a headache for several reasons. 1) space between the pontoons is too narrow, 2) the controls for throttle, shift and steering are more expensive and complex. 3) 50 HP will not be enough power for that much weight. Remember, you will be fighting a pretty strong current in the Mighty Miss. You may find places where your headway is backwards. My suggestion is one bigger outboard of 90 HP minimum.

Give up the idea of cable steering. Much better single push/pull cable steering setups are available at very reasonable prices. Teleflex "No Feedback" for example.

A pair of 24 inch tubes might not be enough for this rig. A tri-toon would be a better setup. Whatever weight you estimated will most certainly be much more by the time you are on the water.

You did not mention electrical system. Since this is a live-aboard rig you will want more than average house power which means at least two, large, deep cycle batteries and possibly and inverter for powering a few AC items. That adds weight.

If you haven't navigated the Mississippi you need to be aware that very large barge tows can be encountered so you need power to get out of their way. 50 HP will not cut it.

Better think about this design more thoroughly!

 

[Dunaruna]

Re: Help me design a pontoon vessel

How fast can the current get?

I have a 45ft 9 ton houseboat with a 50hp bigfoot, she will do 10 knots easily without a headwind.

 

[Silvertip]

Re: Help me design a pontoon vessel

4 - 5 MPH. Right now with water levels as they are, probably faster than that. The problem on the Mississippi is that there are many sharp bends and the navigable channel can be narrow in places. Meet a large tow of barges on one of those blind turns and you need power to get out of the way as the barges can take up most of the river.

 

[Silvertip]

Re: Help me design a pontoon vessel

4 - 5 MPH. Right now with water levels as they are, probably faster than that. The problem on the Mississippi is that there are many sharp bends and the navigable channel can be narrow in places. Meet a large tow of barges on one of those blind turns and you need power to get out of the way as the barges can take up most of the river. As for power -- those two 25 HP motors will need to run at very high throttle settings to make any headway whereas one larger engine at a lesser throttle setting will burn less fuel yet still provide the extra power when and if needed. Yes, twin engines provides the security of an extra engine but it also provides the opportunity for twice as much to go wrong.

 

[tashasdaddy]

Re: Help me design a pontoon vessel

i think this post was already covered just recently. we decided that the 25's were not enough.

 

[5150abf]

Re: Help me design a pontoon vessel

Why not just get an older ponton and strip the furniture off, that would save you alot of work and it would be ready for an engine and sea worthy.

And that is ALOT of weight so you are going to be riding low, our 25'ers with 150 horse 4 stroke weigh 2650, just your deck, camper and tubes are wellover that.

Have you seen the wake thrown by a barge?

Hitting that in a homemade low floating pontoon Ithink would be pretty scary.

Seems like alot of work and expense for something that may or may not work.

I have been in the pontoon buisness for 21 years and while it seems like a fun thing to build your own boat I would really think 4 or 5 times about doing this, especially on the Missisippi, that is some big water for a homemade boat.

 

[Silvertip]

Re: Help me design a pontoon vessel

And a course in river navigation would also be helpful if you are not familiar with the various bouys and what they mean. The term "Red-Right-Return" actually means something. Ignoring a bouy or not knowing what it means can result in serious engine damage from the many wing dams installed years ago on the upper Mississippi. The Corps of Engineers guarantees a nine foot navigation channel. High water, low water, and shifting currents, can quickly alter the character of the river. The river is not necessarily that big from a width perspective, but it can be very dangerous.

 

[jeeperman]

Re: Help me design a pontoon vessel

With todays market of big boats, I would seriously look at buying a real houseboat for pennies on the dollar. How many years do you plan on running this dream? Your post indicates maybe six months?
Buy one cheap and shabby enough so you can walk away from it after your adventure maybe.

Or lease a barge from one of the tow barge companies, plop your camper on top and let the tow push you along with the rest of the barges.