i need carry 30 persond for 10 minutes ride

[RSALVAREZ]

Hi i am a motorcycle and boat mechanic and one of my costumers have a pontoon boat for 15 persons, they ride inside a 80 acres lagoon for 10 minutes at low speed no wake, the ask me to search an used pontoon boat for 30 persons and after search they are on the 20K dlls too many money for a weekend boat. with this in mind i want to build one my idea is use a 165 hp mercrusier powered boat, the boat is a 19 ft vhull sea ray
so, what if:

i can use the boat as power unit and build the pontoon boat around her
i will build a platform around the boat and the pontoons to maximize space this will look like a vhull inside a poonton boat, if my idea work, then the pontoons will be made from wood and fiberglas as is what i can buy and work with it
will draw the idea or any other option?? i will apreciate the help

[Obsession]

Somewhat like this idea http://www.sealver.com/ on a bigger scale. Is the objective to keep the sea ray as a whole and easily separable boat to use on its own too?

[alan white]

The power requirement of a boat going that slow is very small. Even a 4 stroke 20 hp outboard (thruster type) would move the boat along.
A flat-bottomed barge type hull might be a better choice over two aluminum hulls. Something of steel construction with plenty of reserve buoyancy.
To run a big outboard at low (displacement) speeds is a hugely inefficient.
Unless a much higher than no-wake speed is needed, forget the big outboard.

[Obsession]

Agreed - I don't think I'd like the aesthetic of building around this 19' sea ray unless it's totally changed, and if you're going to all the work to make it look nice, sell the sea ray and build from scratch something that looks even better. The boat inside a boat will have a greater draft with the v unnecessary in the lagoon. The connections will probably cause damage to the sea ray over time, especially if that much horsepower is ever applied accidentally. The prop for one use wouldn't be ideal for the other. It would be more complicated to launch and retrieve.

[RSALVAREZ]

Just because the boat is runing, but if build a big flat bottom hull instead of pontoons you mean like a house boat? as courrent they have a pontoon and its work great with the people , i see many plans for sale of barge or padlewheel boats
or like the big catamaran boats
i am not a boat builder and a catamaran or barge or houseboat hull still on the table, the best options are??? a clue from the pro´s??

[RSALVAREZ]

Originally Posted by Obsession

Somewhat like this idea http://www.sealver.com/ on a bigger scale. Is the objective to keep the sea ray as a whole and easily separable boat to use on its own too?

yes i can leave installed will be overpowered but at this stage for me will reduce time and cost if i just build the big pontoons and external structure
as this just will work for 1 week, i am working on the drawing, and again if other option are the most apropiated i can change the plans
thanks

[GTO]

I feel I must be missing something.

If all you truly want to do is drag 30 people around an 80 lake for a few minutes at walking speed, well you could do that with basically a raft and tow it with a jet ski or utilize an electric trolling motor. So am I missing something? Otherwise it seems you are going for a complicated solution to a fairly easy problem.

In fact if you feel you are fully capable of building and mounting pontoons to a powerboat successfully, I would suggest dropping the powerboat out and just build a simple pontoon/catamaran.

Calculate the weights involved, along with a safety factor for having all 30 people try to stand at one end or side of the boat (or add rails to keep the herd where they belong). Build box-like pontoons with a 45 degree upward angled bow and a deck to hold the people and put small motor on the back.

Simple idea from a simple person.
Good luck!

[RSALVAREZ]

Thanks i was talking with a friend this mornig , he is a naval architect and told me a similar response as i will be at no high speed with no wake then (they don´t use their 24 foot pontoon on windy days) he sudgest me 2 square pontoons and an small engine for all of us who love navigate on water is a great ride whe we fight with wind and wave´s and can return to our dock but for people who dont know a boat or even swim this pontoon is their first steep on boating. we are simple persons and is what we need a simple and safe floating deck
you dont miss nothing GTO, just i was trying to use the old seaRay for propultion. thanks for the reply

[messabout]

GTO has given important advice. Arrange the boat in such a way as to have crowd control. Have your NA friend calculate the pontoon size such that they will both support more than 6000 pounds or 2700kg without serious heeling. That is the first order of design. A pair of square or rectangular pontoons will be perfectly suitable if they are suficiently bouyant.

Statistically ferries are the most dangerous boats of all. It is not the ferries that are dangerous but it is the people who ride them that constitute the danger. The people have insufficient discipline or knowledge of boats. They are famous for rushing to one side of the boat in order to view some interesting thing or other. Many ferries capsize because of that. Historicly, the worst locations for ferry tradgedies apears to be Southeast Asia and Indonesia. Egypt and the Nile are not far behind in tragedy happenings. Recently, for example, the Dumas Express 10, off Sumatra, sank and dozens went missing....Two ferries collided on the Nile and 50 people went missing. These realities should not deter you from building the boat. Just be sure of your design and arrange some sort of positive crowd control that goes beyond mere verbal instructions to them.

[rasorinc]

Build your wood platform and sponsons and put a V in the rear and use the Sea Ray as a pusher tug. Here is a easy 24' build just put a canvas top on it to proteck folks from the sun. http://glen-l.com/designs/hankinson/waterlodge.html
You can widen it out to 10' or even 12'

[RSALVAREZ]

Here i end with a conclucion to this as i will be on the displacement hull at very low speed i dont need the searay, just will build a safe platform based on your links and comments to this post as i will navigate at low speed on a confined lagoon
i can use the waterlodge or a plastic drum pontoon as long all must be easy to find in the area
I LOVE THIS FORUM AND ALL THE HELP THAT I HAVE HERE, YOUR FRIEN IN THE BAJA CALIFORNIA PENINSULA, ROBERTO ALVAREZ
WILL POST THE PHOTOS OF WHAT I WILL BUILD WITH THIS INFO

Roberto, consider these as they are near-indestructable, modular (you can transport) and there are used ones on the market. I have used them and they are fantastic. http://www.flexifloat.com/(S(ohgbrei...D=applications Good luck

[ancient kayaker]

Would this work: unhook a floating dock and push it with the pontoon? Tether them together firmly and put rails up to keep the crowd in the middle 50% of the decks area.

[sandy daugherty]

Knock the house off a pontoon houseboat. It will have everything you need already. Power it with two High Thrust 25 hp outboards, propped for 6 or 7 knots at 3/4 throttle. Viola'!

There are dozens of near derelict houseboats on inland Lakes in the U.S. and they can be trailered.