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View Full Version : width compared to length?



riverrats52
02-24-2015, 08:51 PM
Is 12 feet wide by 35 feet long tritoon (3 pontoons) in good proportion for stability and maneuvering? I've heard width and length needs to be in certain perportions. I'm wanting to buy the pontoons-maybe 30 inch diameter and build a 20 ft cabin.

OLD HOUSEBOATER
02-25-2015, 05:07 PM
Fine the wider the better for deck space. Know how your going to transport it though.

riverrats52
02-25-2015, 06:12 PM
Fine the wider the better for deck space. Know how your going to transport it though.

I would build it at my house and have a moving company to transport it to the lake I would stay on--thank you very much.

Tony B
02-26-2015, 11:54 AM
If you were building with a normal power boat hull (planning, semi-planning, etc.), the ratio would be about 3:1 which would definitely put you in the ballpark. However, you are going with pontoons, which is a totally different dynamic since each pontoon becomes a separate hull. Generally, the wider, the more stable. I think your limiting factors would be how far you can span between hulls which would be an engineering question. The easily found solution would be "what are the manufacturers using". The other limiting factor would be how wide are the slip spaces that are available to you? In your case, neither would apply if you only want a 12' beam because you are probably well under the standard beam (width) for that length.
The only place I can see you getting into trouble would be using smaller than normal size pontoons for that length boat just because you plan to carry less weight. That could be a stability issue. Loading weight could play into this some. F'rinstance, too many people sitting all on one side. And a fly bridge, adding weight up high will be a stability consideration.
Curious question, how come you only want 12 feet? After all, you are the builder and you can have what you want. A walk around deck will really shrink your interior.

I built my own ultra-light airplane from scrap parts and taught myself to fly from reading books. Not knowing anything about aeronautical engineering, I studied the specs on well over a dozen manufacturers models. They all had almost exact specs on the dimensions. I cant remember that far back but I think all the wingspans were between 30 and 32 feet. All the chords (wing edges from to back of wing) were 5 feet. all the overall lengths were around 16'. Like I said, I cant remember the exact numbers, but you get the idea. There is probably a really good reason that most manufacturers specs are almost exactly the same for any given length pontoon boat. Once you know the reason, then maybe and only maybe, you can know what deviations you can do from their plans.
The same goes for engine sizes. There are simple formulas for that. Without understanding what you are doing, you can way overspend on a motor, or even worse - under spend.

Tony B
02-26-2015, 12:34 PM
This should be a big help to you: Glen-L.com. They sell boat plans and are excellent people to deal with. .
When you get on their home page, a few inches down from the top and on the left side, hit "Boat Plans Catalog". Then drool over the houseboat plans. It's nice to know the specs BEFORE you build.
The plans include building your own pontoons. here is a photo that someone sent to them from one of the plans that shows the pontoons under construction. http://www.glen-l.com/designs/house/dsn-hfnc.html .

Once you buy their plans, they are dedicated to help you succeed. You can ask loading questions and they can usually tell you how far down you will sink for each additional thousand pounds. That alone would be worth the price of the plans. Way back when, I had built 3 different boats from their plans.
They all went exceptionally well. They even tell you what size motors to put on there and what to expect if you go larger or smaller. That alone can save you thousands.
Anyway, have fun pawing through the houseboat section.
If you don't buy their plans, they wont help you, however, from their online plans info, you can pretty well figure out what to expect if you made your own from your aluminum pontoons.
best of luck and have fun.

Fork-lift-king
02-26-2015, 12:37 PM
Check your private messages.

riverrats52
03-03-2015, 02:01 PM
I don't see anything in my messages??

riverrats52
03-03-2015, 02:11 PM
I am thinking economically on size=fuel use, slip rent, etc. cabin will be all way across deck, no catwalk. live aboard for one and a dog or maybe two people with very little visitors. I don't have the money for BIG and too old to go in debt. Plan to be anchored out whole lot. I don't have experience with houseboats so need small to learn to get back into dock. Thank you Tony B. -I enjoyed that glen-l site! I am determined its never too late to live out your dream-even if I cant convince my husband I will find a way!

Endurance
03-04-2015, 09:23 AM
Tony brings up a good point about the material you use to span between your pontoons. For what it's worth, I have an 18 foot wide pontoon boat on which the manufacturer spanned between the pontoons with aluminum C channel crossmembers that are 4" high (called the web) and have legs (called the flanges) that stick out 2". The web thickness is .150" and the flange thickness is .230". The material is 6061 (also called T-6) aluminum and the manufacturer spaced the crossmembers on 12" centers. The choice of 6061 is a good one since it approximates the strength of steel with a lot less weight and a lot better corrosion resistance. Aluminum like this generally comes in 25 foot lengths, so a 12 or even a 12.5 foot wide boat would limit waste.

I'm also with Tony that for a pontoon boat, the wider the better. That's especially true if you have twin engines. The wider you can space twin engines, the better the boat maneuvers at low speeds. You'll also see less side-to-side rocking in open water with a wider boat.

You will probably want to give some thought to the issue of insuring your boat. Some insurers don't like homebuilt boats. Amelia (one of the frequent posters here) might be able to help with that issue.

riverrats52
03-04-2015, 01:32 PM
Is it possible to get ABYC credentialed inspectors to inspect the boat in stages of building to affirm it is built to standards for insurance?



Tony brings up a good point about the material you use to span between your pontoons. For what it's worth, I have an 18 foot wide pontoon boat on which the manufacturer spanned between the pontoons with aluminum C channel crossmembers that are 4" high (called the web) and have legs (called the flanges) that stick out 2". The web thickness is .150" and the flange thickness is .230". The material is 6061 (also called T-6) aluminum and the manufacturer spaced the crossmembers on 12" centers. The choice of 6061 is a good one since it approximates the strength of steel with a lot less weight and a lot better corrosion resistance. Aluminum like this generally comes in 25 foot lengths, so a 12 or even a 12.5 foot wide boat would limit waste.

I'm also with Tony that for a pontoon boat, the wider the better. That's especially true if you have twin engines. The wider you can space twin engines, the better the boat maneuvers at low speeds. You'll also see less side-to-side rocking in open water with a wider boat.

You will probably want to give some thought to the issue of insuring your boat. Some insurers don't like homebuilt boats. Amelia (one of the frequent posters here) might be able to help with that issue.

Bamby
03-04-2015, 02:44 PM
Is it possible to get ABYC credentialed inspectors to inspect the boat in stages of building to affirm it is built to standards for insurance?

I doubtful that you could actually get anyone to come to your place and inspect it in stages and even if I'm sure it would get expensive. When I did mine I took a lot of photos throughout the entire build. And like you I had to summit to the state for them for a state issued title and vin number for the boat. For me at least it was pretty painless fact is a lot less painless than I ever contemplated it would be.

A state ODNR Officer was attending a event a a large sporting goods retailer near my place. So I packed my photo album and jotted down some notes about a few completion issues I needed clarified and went off to talk to him a bit. It was pretty darn neat he sat down and looked through the album asking a few questions here and there while also answering mine. He then said all he needed was to borrow a few photos from my album to take back to his office and he'd complete the title and vin paperwork and I should receive everything back in the mail in a week or two. He was good to his word too, rec'd it and my photo's back ans was saved the agony of hauling my boat a hundred miles of more to their usual point of inspecting such projects.

As far as insurance goes on mine we went with declared value. We found a value that was high enough that should we have suffered a total loss we wouldn't be out much. It should have been about 10K more on the boat but they wouldn't go there so we put it in contents.

riverrats52
03-04-2015, 02:47 PM
Thanks -good info


I doubtful that you could actually get anyone to come to your place and inspect it in stages and even if I'm sure it would get expensive. When I did mine I took a lot of photos throughout the entire build. And like you I had to summit to the state for them for a state issued title and vin number for the boat. For me at least it was pretty painless fact is a lot less painless than I ever contemplated it would be.

A state ODNR Officer was attending a event a a large sporting goods retailer near my place. So I packed my photo album and jotted down some notes about a few completion issues I needed clarified and went off to talk to him a bit. It was pretty darn neat he sat down and looked through the album asking a few questions here and there while also answering mine. He then said all he needed was to borrow a few photos from my album to take back to his office and he'd complete the title and vin paperwork and I should receive everything back in the mail in a week or two. He was good to his word too, rec'd it and my photo's back ans was saved the agony of hauling my boat a hundred miles of more to their usual point of inspecting such projects.

As far as insurance goes on mine we went with declared value. We found a value that was high enough that should we have suffered a total loss we wouldn't be out much. It should have been about 10K more on the boat but they wouldn't go there so we put it in contents.

Tony B
03-05-2015, 07:59 AM
Just some thoughts about personally designed and built boats.

1).You can get insurance, but the amount of companies that will cover you are probably limited.
2). Custom boats that are home built usually are amateurish looking and if you sell it, you will probably only get pennies on the dollar. And that make take a while. This also includes major
modifications inside a factory built boat, such as adding cabinets and storage units that the original manufacturer had not intended. Minor changes are usually OK.
3). Sometimes, what is already available on the market will be less expensive that what you can build yourself and quite often of a better quality. The mere fact that you came to this forum with a fairly basic question means you don't have any experience in boat design. This is not to say that you cant build a great boat. Just saying that it is unlikely.
4). Statistically, most home built boats never get finished. There are various reasons such as the time it takes to build and the cost was way more than expected. Building a boat yourself is similar in respect to buying a 'project' boat in that your new hobby will be boat building and not playing on boats. Each person has different hobbies and interests. Boatbuilding may be yours.
5). If you really want to build your boat "just because", I can certainly understand that. I had a commercial woodworking business after 20 years as an engineer. I built 3 boats from Glen-L designs.
I would highly recommend their plans because of the full size patterns on the frames and their detailed instructions and their book on wooden boat building. Their assistance along the way was great.
With purchased plan/blueprints, you will not be going into this blind. You get a materials list for free on their website. That will give you an idea of some of the costs. As far as insurance is concerned, you will have all of the technical data. If you have any questions on how to load and balance the boat, they are their. You wont over spend on an overpowered motor. If you bought their plans, they wont help you much if you purchased your own aluminum pontoons, but you could find the buoyancy of your purchased pontoons as compared to building your own from plywood and cover with fiberglass. This would help in load and balance.
Design is very important. Over-building is not necessarily a good idea with boats, especially with wood structures. Boats are continually flexing and 'moving' in the water. Not stable like a house on solid ground. In our eagerness to make it stronger, we will be making it heavier. Home-built boats have been known to collapse under their own weight.

I wish you the best of luck in your endeavor, whatever you choose to do.

riverrats52
03-05-2015, 01:59 PM
Thank you-I have researched and decided I'm not experienced enough so I need to abandon the build it plan! :( I wanted to build it because I wanted my floor plan backwards (salon and galley in back) and back deck the biggest for more use than front deck, and I've not seen ANY boat that way-so maybe there are reasons should not be done or just no one else would want one that way? Thanks for all the info everyone. Now to get the house we live in sold so we can buy!


Just some thoughts about personally designed and built boats.

1).You can get insurance, but the amount of companies that will cover you are probably limited.
2). Custom boats that are home built usually are amateurish looking and if you sell it, you will probably only get pennies on the dollar. And that make take a while. This also includes major
modifications inside a factory built boat, such as adding cabinets and storage units that the original manufacturer had not intended. Minor changes are usually OK.
3). Sometimes, what is already available on the market will be less expensive that what you can build yourself and quite often of a better quality. The mere fact that you came to this forum with a fairly basic question means you don't have any experience in boat design. This is not to say that you cant build a great boat. Just saying that it is unlikely.
4). Statistically, most home built boats never get finished. There are various reasons such as the time it takes to build and the cost was way more than expected. Building a boat yourself is similar in respect to buying a 'project' boat in that your new hobby will be boat building and not playing on boats. Each person has different hobbies and interests. Boatbuilding may be yours.
5). If you really want to build your boat "just because", I can certainly understand that. I had a commercial woodworking business after 20 years as an engineer. I built 3 boats from Glen-L designs.
I would highly recommend their plans because of the full size patterns on the frames and their detailed instructions and their book on wooden boat building. Their assistance along the way was great.
With purchased plan/blueprints, you will not be going into this blind. You get a materials list for free on their website. That will give you an idea of some of the costs. As far as insurance is concerned, you will have all of the technical data. If you have any questions on how to load and balance the boat, they are their. You wont over spend on an overpowered motor. If you bought their plans, they wont help you much if you purchased your own aluminum pontoons, but you could find the buoyancy of your purchased pontoons as compared to building your own from plywood and cover with fiberglass. This would help in load and balance.
Design is very important. Over-building is not necessarily a good idea with boats, especially with wood structures. Boats are continually flexing and 'moving' in the water. Not stable like a house on solid ground. In our eagerness to make it stronger, we will be making it heavier. Home-built boats have been known to collapse under their own weight.

I wish you the best of luck in your endeavor, whatever you choose to do.

Tony B
03-05-2015, 06:58 PM
I think you made a wise decision. I'm sure if you look hard enough, you will find a houseboat that fits your needs or can be modified to your personal likes without too much work.
Check out places like yachtworld.com and search all of the manufacturers. Look at their layouts and see if you can retro fit any of them to your likings. Then, look for a used boat in your price range.
Hope you don't abandon this forum. Many people join forums and take several years to actually find and buy their dream.

easttnboater
03-06-2015, 06:20 AM
There are reverse layout houseboats out there. It is a relatively new design. Some folks on my dock just had a new Thoroughbred 17.5 x 80 delivered with the reverse layout. Inside it is very, very nice. It does look funny from the outside though.

riverrats52
03-06-2015, 08:38 AM
oh I won't abandon this forum! I'm learning too much info. I been looking at used boats on internet for 8 years-since we sold house to live aboard and husband changed mind at last minute. Now he wants to again and now we have another house to sell first! Just thought I would go ahead and start now if build--but decided to buy so have to sell house first! I wanted reverse floor plan so when at dock can look behind at water instead of at houseboat across dock--back to dreaming again instead of making a reality. temporary though--when house sells houseboat here I come-with or without hubby--sounds awful to those who don't know me I know.


I think you made a wise decision. I'm sure if you look hard enough, you will find a houseboat that fits your needs or can be modified to your personal likes without too much work.
Check out places like yachtworld.com and search all of the manufacturers. Look at their layouts and see if you can retro fit any of them to your likings. Then, look for a used boat in your price range.
Hope you don't abandon this forum. Many people join forums and take several years to actually find and buy their dream.

riverrats52
03-06-2015, 08:41 AM
So I'm not the only crazy one with backward ideals!! Much too big houseboat for my pocketbook though!


There are reverse layout houseboats out there. It is a relatively new design. Some folks on my dock just had a new Thoroughbred 17.5 x 80 delivered with the reverse layout. Inside it is very, very nice. It does look funny from the outside though.

Tony B
03-06-2015, 01:06 PM
................ I wanted reverse floor plan so when at dock can look behind at water instead of at houseboat across dock--................


I'm really confused now.
If its the view you want, you can either pull in or back into a slip. I've never heard of any rules on that.
We always pull into a slip so that we can be on back deck in privacy. Not only a better view, but we don't have to see people going up and down the dock.

Endurance
03-10-2015, 09:33 AM
Tony, I think you're going the same direction (sorry, bad pun) as the original poster. The difference is that, unlike pointy-end boat, a usual houseboat has most of the living area like the salon and the galley at the front of the boat. A typical houseboat has the master suite at the back of the boat. So making what the original poster called a reverse layout would put the galley and salon at the back of the boat, much like your boat is now.

It's true that, in theory, you could just back a houseboat into a slip. Maybe I lack docking skills, but I think that would be more difficulty than I would want to tackle on every boating trip. It might serve someone well if they had what I call a "slip queen" that rarely went out on the water.

The real beauty of a reverse-design houseboat if you find yourself beaching on boring shoreline. With the galley and salon at the back of the boat, you do your cooking and living at the back of the boat where you have unobstructed view of the water. The reverse layout has less appeal if you like to watch your kids build sandcastles on the beach.

Stmbtwle
03-28-2015, 07:04 AM
Backing into a slip isn't that difficult (with twin engines and PRACTICE), sport-fish captains do it all the time. The trick is keeping the bow under control while you maneuver the stern. On houseboats like mine, visibility would be an issue, too.

The reverse layout would have lots of advantages at anchor, as the kids could swim and fish and guests could visit in full view of the main cabin.

Maybe Amelia will chime in... I think their boat has a reverse layout.

Amelia
03-28-2015, 07:32 PM
I like the reverse layout for our situation. Wondering how people kept soaking-wet kids from tossing soggy towels on the bed on their way in from swimming, we opted not to put the main bedroom aft athwartship as most commercial houseboats seem to do. This way, we can sit at the table, intercept the drippy ones, and watch the sun set, fix supper together, and watch the passing scene in bug-free comfort. At anchor in some idyllic cove, we can rock on the generous back deck out of the wind with an evening libation and watch the stars come out. It's easy to toss the kayak in the water and watch the children play, opening the 8' sliding glass door up to nearly double the entertainment space. It works just fine for us, so far. Might not work so well if you needed to find sleeping space for 12 in this many square feet, but for two of us and very occasional little people, it's generous. I can stand in my big aft galley, and peer forward and see where we're headed, underway, too.
As for backing into the slip, we have two secrets. First, we installed a trucker's or RV back-up camera on the aft starboard corner, up high, aimed slightly down at the dock. Takes a little getting used to the very wide-angle lens, but it's really helpful for the big picture. Second, we invested in headset walkie-talkies, so we didn't have to yell at each other as if we were having a terrible row. So Rob stands on the back deck, watching, giving instructions to the she-monkey at the helm, "No, the OTHER starboard. Starboard power Forward. Port engine back just a little. Perfect. Now, come on back. straighten it out. " And so forth. Then makes the lines fast. We're getting a lot better at it. Or were, before it got too cold. Now we'll start learning all over, before too long!