Non planing or planing Tritoons?

I'm new to this forum but I've been boating all of my life. I hope I'm posting in the right place, if not please let me know. I've owned 5 houseboat and a half dozen runabouts and I do all my own work maintaining and improving them but I'm no engineer. I'm near a 130 mile long lake In Arizona and getting around quicker than I have been is becoming a premium. My current houseboat is a 99 Jamestown displacement hulled 16x58. It is powered with two 3 liter Mercury I/o's, seems fine, reliable and easy on fuel. I cruise at about 7 miles an hour but with recently lower lake levels some short cuts are closed and the beaching/camping spots are 40 milers away.
So I'm interested in building a faster lighter pontoon boat that is kind of a Sport Utility Boat. Something that is a comfortable day boat with the speed of a cruiser. We operate on a hard bottomed deep lake, solid rock, so to me cruisers are not ideal. Beaching is easier with houseboat designs but they are slow. I want to bridge the gap and build a roomy pontoon boat that can be either a day boat or overnight camper. My inspiration is one I've seen in a yard and the elderly owner loves it, it was custom made in the 80's. So a solid roof made from aluminum with open walls with the option to close them up with canvas is what I'm looking to do. I've found an old water taxi that was used on the Colorado river south of Las Vegas at Laughlin. It's been converted to a solid walled houseboat but I think it's could be good raw material for my project. So here is the question, Can anyone tell me if these pontoons will plain? I think they are displacement rather than planing but I'm not sure. Also the dimensions of the boat is 10x35 and there are two 60 hp 4 strokes hanging on it. If I were to strip it down and it weighs less than 5,000 lbs how fast in general terms could I expect to go with these pontoons and say 60's? With 200's? Id like to get some educated feedback on what I might expect before I buy this boat. Or would I do better starting from scratch with a new build pontoon boat? Thank you for any feedback.

 

Welcome to the Forum CC.

What is the budget that is available for your new boat?
That is perhaps the most important aspect here.

How big does your new boat have to be, and how many people, how much stores, will it have to be able to carry?
Are there refuelling stations along the lake, or do you need to have an impressive range if you want to go from one end to the other and back without refuelling?

Does it absolutely HAVE to be a pontoon boat?
I am wondering if maybe a power cat with a more 'conventional' hull shape might be more suitable for what you want to do?

Richard Woods has very nice power cat designs - @fallguy on this Forum is currently building a 32' Skoota.
Sailing Catamarans - Click here for Power Catamarans (8 designs) http://sailingcatamarans.com/index.php/designs-2/6-powercats

And Bernd Kohler has some very nice catamaran houseboat designs available -
POWERcats https://ikarus342000.com/POWERcats.htm

And there are MANY other types of power catamaran designs available on the web as well.

 

Thanks for your feedback. I'll look at the other ideas you posted links for. Our main short cut up lake is closed and may be for the foreseeable future, it adds an hour and a half to an up lake beaching and camping trip. House boating is the number one recreation on this lake, the most common type of boat. I was thinking of Tri toon for the deck space, Premier builds one commercially that has a pair of 360hp mercuries on it. It can run in the 50 mph range. That one is 10 wide by 36 long, so I'm kinda fascinated by pontoon boats and the advances between pontoons and outboards. Again for beaching pontoons are great. This lake has sheer canyons walls so finding Anchorage to the bottom is sometimes impossible, the drop offs are sheer. Beaching straight on and anchoring to the wet sandy beach line is easiest, beaching is the name of the game here. Since I own three other boats I'd like to keep my budget on the lower side. I've been pondering such a boat for a couple of years now, I'd like a head and shower, a simple outdoor kitchen and pontoon furniture that converts to a couple of beds. I've drawn up 10x35 shapes scaled to hold those things and it seems to work. I also have the advantage of copying and existing real world prototype. I'm also a home builder so I know my way around the floor plan and house part of a houseboat. I would be satisfied with anything over 20 mph and I like the idea of starting with an existing craft. These look like non plaining pontoons, like they would be more like a catamaran style. Do you have any idea if I could see speeds over 20 mph with these? Please advise.

 

You don't arbitrarily add horsepower to a vessel. They all have limits and rating plates or if no rating plate, then practical limits.

Check out the GT23 and GT27 on boat builder central.

 

Thank you for your response, you might know more than me about boat design. I've read practical information like that here but I've also read other threads on this site where there was consensus to beef up your transom and add some power within reason and theoretical limits like you say. I'm willing to try, if I sink it I'll pay for the recovery and scrap it. I've hot rodded everything from Planes to Porsches so I'm not super risk adverse. This boat was built sturdy for commercial use and there is no transom plate for power or weight limit rating. It's already experimental with that custom structure on top. I'm looking for any information about the type of pontoon design and what the theoretical speed limit might be of this pontoon design.

 

From the photos you posted they look like displacement hulls. That is not a shape for planing. to plane a pontoon boat takes a lot of HP and the right shape. You are right that pontoon boats are ideal for the activities you want, but pontoons are not intended to be runabouts. If you want to go fast it's best to get a boat designed for speed. If you want a boat that is basically a houseboat on pontoons you're going to have to resign yourself to a slower pace.

 

Thank you, that makes sense. However Tri toon boats that plane regularly run in the 20 to 30 MPH range with just 150hp. Does anyone believe that a non Plaining Tri Toon tapered front and rear could run in that range or is it just not possible?

 

I don't think so.
The simplest type of planing pontoon hull would be a rectangular box, with the front end curved up to help lift it up, so that it is not acting like a bulldozer.
If you build a catamaran with two of these hulls, you will get the most 'bang for your buck' re buoyancy and planing - but with a downside that if the water is even slightly choppy they will slam.
Everything is a compromise in boat design, and you just have to try to find the best compromise that suits your needs.

 

I would say the pictures show a boat that does plane, the bottoms are seemingly flat, but they do taper at the stern to reduce the 'suck" of an abruptly ending pontoon, to what good effect is debatable though. The central one the same, but it is certainly not optimized for either planing or displacement mode

 

Thank you for that, I'm a layman but that's kind of what I thought too. This boat was built by The Boatel/Blue Water Yacht corporation. All of Boatels houseboats featured steel pontoons but these are aluminum. Someone engineered these, they are similar to the houseboat pontoons, they are chambered, deep and angular but tapered at the front and rear. I'm curious about how they will perform. At this point I'm going to buy the boat and run it on the lake with a GPS devise in hand. If it runs into the the mid teens as is then I'll pursue a refit/remodel into my purpose built, fast(as houseboats go) day out beach invader. If it just rides stable and smooth at 8 mph I'll clean it up and pass it onto the next starry eyed dreamer. I'm also a dealer and installer of a product called Hydrofin. They are hydrofoils for pontoon boats and they work really well. I may install a set under this boat to see what happens if I can get it to go 20 mph and I can get it light enough for them to be effective.

 

What is missing here is a picture of the bottom of the pontoons. If they are flat, they may very well plane. It would depend somewhat on the width of the flat section.

When pontoon boats first came out the pontoons were built round because they were cheaper than making them with ( square/rectangular/) flat surfaces. The circular shape minimized flex. To keep flat surfaces from flexing, you would need to either go to increased
wall thickness or a comprehensive set of inside stringers/longitudinal supports. Both methods expensive, material and welding costs.
Rolling a sheet and welding one full length weld (possibly with bulkheads throughout the length) was much easier from a manufacturing viewpoint.
Most of the early models had low horsepower and were just moving decks, party boats if you will.

Then people decided, like you, that you want to go faster so they added a bunch of horsepower and they could push these boats into the 50's and also offer enough speed to pull skiers, wakeboarders and tubers. So one boat could service
two purposes, a tow boat as well as a party boat ( a missing use is of course wake surfers but I would not doubt, and maybe someone has, developed a mechanism to produce a tall wake with a pontoon boat

So the higher horsepower could get a pontoon boat to high speeds but the round convex shape was not efficient (efficient defined as a poor miles per gallon of fuel when planing) So the manufacturers decided to install
lift strakes, or flats, or various shapes to the round bottom of the toons to increase efficiency. The addition of planing enhancers added to a round toon was cheaper still than making a cross section with flat sections and omitting the round
base profile.

Will round tubes plane, certainly. Will tubes with strakes plane more efficiently, yes. Would tubes designed with full flat sections or turned down chines, presented to the water plane even more efficiently, yes but it would come at an
increased manufacturing expense

So a picture of the bottom of the pontoons from the above boat would help deciding if you could get this boat to plane with reasonable horsepower.

Certainly the rear tapered section will help at displacement speeds, but they should not inhibit or reduce its planing ability with the exception of slightly lowering the planing surface.

If the bottom of the current toon is flat, measure it and then ask the question to the NA's here. Query: The flat section is 12" wide. Will these 3 flat planing surfaces provide significantly more or less lift than say a 24" round toon profile

If I were trying to get a handle on this, I would visit some websites of pontoon boat builders who have been around a long time. Look back at their very old pure round toon models, ie no flats, check out horsepower and speed specs
Then look at the new ones to check the modifications and new specs. At least you might get a little closer to answering your question

 

how quick is that

 

excellent post Barry