Re-Inventing The Wheel, Again

[ElGringo]

Hello, I am new here and I have a few questions and later when I have all the info I can gather I will spring my idea on you.
1. What does the average 24', two tube pontoon weigh?
2. What is the clearance from the bottom of your deck to the water?
3. How much horsepower does it take to maintain 20mph?
4. Can you use your boat when there are whitecaps on the water?

[BobG]

Hello, I am new here and I have a few questions and later when I have all the info I can gather I will spring my idea on you.
1. What does the average 24', two tube pontoon weigh?
2. What is the clearance from the bottom of your deck to the water?
3. How much horsepower does it take to maintain 20mph?
4. Can you use your boat when there are whitecaps on the water?

1. More than an African Swallow. My tritoon weighs 3000 pounds.
2. About 16 inches.
3. I would guess about 90.
4. Depends on how you use it. I've been out with waves breaking over the front fence.

[ElGringo]

Hi Bob,
Is that weight a ready to go weight? I'm needing a everything but the motor weight. I guess the low height from the water is the reason for adding a skin to the bottom? I wonder if a 90 would burn more fuel than a pair of 18 to 25's? On the whitecaps, would you start a trip in those conditions or is it just that you were caught out and had to do it?

[BobG]

Hi Bob,
Is that weight a ready to go weight? I'm needing a everything but the motor weight. I guess the low height from the water is the reason for adding a skin to the bottom? I wonder if a 90 would burn more fuel than a pair of 18 to 25's? On the whitecaps, would you start a trip in those conditions or is it just that you were caught out and had to do it?

Good question. 3,000 pounds is my dry weight, less motor. Add the 400 pound motor, fuel, gear, and crew of 2, and it could easily be over 4,000 pounds. We're talking 16 inches on 25 inch toons, so only 9 inches of the toon is in the water at the bow - more like 12 inches at the stern. If I were going dual motor, I would want at least dual 90's (of course I also would like a single 200). I've started trips with white-caps, but really in a tritoon whitecaps are no big deal. Now 3 to 4 foot waves are quite another matter. I got caught out in that, and had no choice but to ride it out.

[ElGringo]

I have been talking to several boat designers and can not find the exact thing I want which is a pontoon type deck with catamaran hulls. Richard Woods has a design called a Skoota 28 that has the hulls I want to use. Here is a link to it http://www.sailingcatamarans.com/index. ... -skoota-28 It uses twin 20 hp, weighs about 5,500 and the 20's push it around 17 to 18 mph all day long. The shape of the hulls being the main differance. The designers I have talked to all tell me that a round tube while being efficient at holding up the load will always take 3 to 4 times the horses to push it. I want about 36" of clearance under the deck to the water when loaded. I'll post a picture of (close to) what I want.

[BobG]

That Skoota 28 looks awesome! You have to disassemble it to take it down the road, but the result is a boat with a 12 foot beam. Very interesting! VERY interesting!

[ElGringo]

I would like to build one simular to the picture as a 10 X 24 with around 20' usable deck made in 3 or 4 pieces. Still undecided on what type of wheelhouse but I do know I want it off the water by 3' I keep thinking I want to play in the Gulf of Mexico a bit. If, and that's a big If at the moment, I want to power it with a pair of 20's and have the whole thing with motors and fuel weighing around 2,500. I have the hulls figured out with some alterations to the plans for the 24' one in the picture and the Skoota 28. Both the hull shapes are within a degree or two of being the same. The Skoota is just larger and uses stringers. The 24' has no stringers and is using the chines to stiffen the hulls. I don't like that idea so much.

[tuned]

I would like to build one simular to the picture as a 10 X 24 with around 20' usable deck made in 3 or 4 pieces. Still undecided on what type of wheelhouse but I do know I want it off the water by 3' I keep thinking I want to play in the Gulf of Mexico a bit. If, and that's a big If at the moment, I want to power it with a pair of 20's and have the whole thing with motors and fuel weighing around 2,500. I have the hulls figured out with some alterations to the plans for the 24' one in the picture and the Skoota 28. Both the hull shapes are within a degree or two of being the same. The Skoota is just larger and uses stringers. The 24' has no stringers and is using the chines to stiffen the hulls. I don't like that idea so much.

Interesting concept. Keep in mind that most states only allow102" max without extra permits and a chase car etc....
I LOVE the idea of a shaped hull. I can see where the improvement can be gleaned as long as you can keep the weight down.
Pair of twenties would be very efficient, but think about powering up a bit. At the very least overbuild your transoms so that you have the option to go to 50s (which is a very common motor size). Or even 90s if you're feeling frisky, which is the next most common size.
I can tell that you have a bit of knowledge in these areas. Good luck on your build. Looking forward to watching it GO! We have a 'Build' section on the forum if you like to start a longer thread and document the whole thing start to finish.
Don't forget the

[ElGringo]

Tuned, The 102" rule is the reason I need to make the deck in two or more pieces. I would like to be able to get it off the trailer and assemble it by myself. This would involve some type of very short wheeled cradle for the hulls. The Skoota 28 can handle up to a pair of 60's and the 24' pontoon/catamaran can handle a pair of 40's as they are designed. I am not going to start the project untill I have a lot more information. Boat designers are not real interested in sharing their knowledge and seem to be locked into a "This Is The Way it Has To Be Done" because it always has been. Then they go into their sales pitch for one of their designs. I understand that they need to make a living But, they just don't have what I want. If you ask about making changes they instantly go into a "it will throw the whole thing out of balance, and it will sink, and you'll get killed" routine. I think a lot of that is B.S. they just want you to buy their plans and go away.

I have learned that if your pontoons were shaped a bit and farther apart you could go just as fast with half the horse power.

[playcat]

There is a fair number of power catamaran builders already, some with full planing hulls and some use round bottom displacement hulls. No need to reinvent the cat when its been done already. Check out World Cat, Power Cat and a few others with some Bing-ing, Yahoo-ing, Google-ing...

[ElGringo]

Playcat, None of them build one like the picture above and, most of the smaller (less than 35') catamarans are fiberglass, very heavy, and more like a tunnel hull than a catamaran. None of them are 10' wide and none of them can be dis-assembled, trailered, and re-assembled by one person. I have been looking for about 6 to8 months and if it's out there, I can't find it. If you run across one, I would sure like to have the web address.
Thanks