Trailerable houseboat designs

I've built 4 small boats, the last one being a 17ft center console for playing around the west coast of Florida. Now I'm looking at working up to a bigger project in a few years of a different kind. My wife an I took a trip recently on the St. Johns River in a tiny houseboat, and we had a blast. Here is the boat we rented. It was called a Hobo from the early 70's, and it was only 18ft long and 7.5ft wide.

20210206_080300_resized , on Flickr

20210205_121442_resized , on Flickr

While it was fun, it was a just a little snug for us. We talked, even took measurements while on her, and I think this concept stretched to 21 or 22ft and 8.5ft wide would be great. In that, I would keep the near zero deadrise in the stern, but add some to the front to help it move and cut through as it tended to plow above 6mph. I am not looking to fly down the rivers and intercoastal, but a good cruise of 9-11mph would be great. I would also add a little freeboard as the stern only had about 12" to the waterline, and I wouldn't mind a better safety factor. This would be a foamcore composite build so the structure would be kept light, with the tanks and batteries kept low and center to help with stability. It would be powered by an outboard.

Thoughts? I know there are adventure crafts out there, but they have a lower freeboard then I would like for the waters we want to traverse, weather permitting of course. I'd rather not have a pontoon style houseboat, as the windage is way worse. Are there plans out there like this idea? Would converting an old hull be a better idea and if so suggestions?

 

Your Hobo does look very neat and fit for purpose - I can see how you would have a wonderful holiday in good weather on a river cruise with her.

Re building a new boat, how about this GT 23 from Bateau?
https://boatbuildercentral.com/StudyPlans/GT23_STUDY.pdf?prod=GT23

It is based on a garvey hull, and there are two types of hull offered - the hosueboat hull version is more full forward, and hence has more displacement (and payload).

Re re-fitting an old hull, here is a left field suggestion. Maybe see if you find an old Boston Whaler or similar (as in OLD, where they are effectively giving it away - and if it has been stripped to a hull shell already, then even better) perhaps similar to this one -
1986 Boston Whaler Guardian 22 Saltwater Fishing for sale - YachtWorld https://www.yachtworld.com/boats/1986/boston-whaler-guardian-22-3826764/
then you could maybe build a houseboat cabin on it?
Although these 22' Whalers are only 7'6" wide.

 

Thank you for your reply. So the last boat I built was a Bateau FS17. Just being honest I have some issues with how their plans worked out, and I really want to move away from stitch and glue plywood. I designed my other 2 skiffs, and while basic, I have a good idea of how I want things and how I want the features to work. That said, I do like the GT23, but I'd have to convert the plans frames and stations to work in foam strip, and the bow isn't made for any kind of chop. I've thought about buying the plans just as a guide, and redesign several parts of it like extending the cabin even further as we really liked the bow area for lounging.

Buying a shell and converting it is definitely a possibility. I'm sure there are plenty of old fiberglass hulls around that would work well. Maybe a commercial fishing/crabbing boat. Efficiency is more important to me then being fast. If I can cruise at 10mph without putting out a massive wake I'd be really happy.

 

But she has a garvey type of bow, which should cope well with a bit of chop surely?
And I am sure it would be possible to extend the cabin further forward on a garvey hull like this, especially if you choose the option with more buoyancy in the bow.

Re buying an ex fishing or crabbing boat, be aware that for a displacement type of hull form that is 22' long, your hull speed will be a maximum of just over 6 knots or thereabouts, and a more economical cruising speed would probably be more like 4.5 - 5 knots - hence you would basically have to be planing in order to achieve 10 mph?

 

Problem with converted commercial craft is the weight. Under built for us is over built (read heavy) for almost all recreational purposes. Some of the Bristol bay setnet skiffs are about the specs you want, but most are aluminum. With that said, the boar pictured is a pretty basic hull form with a tall truck topper on top.

A friend wanted to make a coastal crabbers that was under 26 feet with higher sides. He bought a 29 or 30 footer, that had a bad transom. Spent 14 hrs one day with a chainsaw and made it empty and 26. Then swapped in a new transom and off to the races. It did ok, considering the budget he built with.

No idea what happened to it sadly. But it did work ok. Might. Be a potential.

 

Well, I have houseboated about 20 times, so have a lot of experience.

I really want the boat to be beachable, that is the number one requirement. I have beached these on solid stone, cobble, sand, you name it. The steel bottom is what makes it possible. Beachable means you can be safe and away from weather at night. To make a foam core, trailerable hull beachable, you'd need either twin hulls or a barge hull and in either case, some sacrificial runners. I'd want the twin hull option.

Second, we stayed on a couple different versions, but most of them had a screened in and roofed foredeck. It sure is nice.

Third, an escape boat is sort of essential. Fire is the main threat on many boats and you really must have an escape boat you can either tow or tie on the hip or even on the roof, but it must be easy to get on the water. And the best way is a boat capable of getting you to port in an emergency.

That covers some of the basic essentials.

Inside, we froze on a couple, so I recommend allowing for 2" insulation in the roof. It'll also prevent Florida heat from cooking you. Foam core sides would offer some help as well as painting white. The ones we froze on were not insulated, but had heaters that ran no stop and depleted 100 pounds of propane in less than a week. In Florida, you might want an ac rooftop unit.

I like coffee onboard, so some way to make it is good whether a propane top or genny and electric, though the propane is nice and quiet.

We always keep mosquito coils onboard and burn a two inch piece inside before bed. It makes for much more relaxed sleep. Probably a health advisory here..but sleeping with 20 flying around is a bugger. And they hide easily on wood walls.

No hulls in mind, but Barry on bateau is selling the gt23 half finished project for scratch. It might be worth it for a fast finish.

 

It's a semi garvey-ish type hull. The way it is designed, because of the stitch and glue, the keel drifts up as you move towards the bow to accomodate the bends in the ply. The same as my FS17 does. What this does is makes the hull ride on the top of the chop instead of cutting through it, and it makes the hulls pound a bit. If they were adapted to foam strip with the keel kept level for a few more feet I feel it would greatly improve the issue.

The hull speed is something that confuses me a bit. I've gone through the calculators, seen the formulas and all, but that can't be it. If the Hobo can move through the water at 6mph and is shaped like a melted brick then how can a 22ft hull with a more hydrodynamic bow not go faster? My FS17 can move along at 8mph until it really starts to plow.

 

I was just spit balling ideas. There was something about the clam/crab boats we looked at up in Cedar Key that just looked cool to me. Yes the 18ft Hobo is anything but a slick design, but we still enjoyed it. I just want something a little bigger, slightly faster, but still super easy to trailer around.

 

Hull speed for a displacement hull is limited by hull length.

Theoretical max is 1.34 x root (lwl).

Hobomax is 5.7

A boat cannot go much faster with a non-planing hull.

Of course, planing and semi-planing hulls are different.

 

All houseboat hulls I have been on tend to pound. They typically have low deck clearances and high windage. Most commercial rental places will not let you leave their ports or return on winds exceeding 15knots.

 

Thanks. I'm not sure if you are states side, but I think you are using your houseboats differently then my program would be. There would be no real beaching, since most of the areas we would be in are very well protected we just need to drop anchor in a protected cove. if there was any beaching it would be on sand, and you don't see many steel hulls around here, just fiberglass and aluminum.
Screens are a must in Florida, or at night the skeeters will carry you away. The Hobo had screens on the windows and they did the job well.
I don't know about an escape boat. The majority of the waters we frequent we can basically stand up in, or swim to shore within 100 yards. we might have an inflatable dingy and small motor for the times we are moored, or want to do some fishing. That said, I'm actually buying a new PLB in a few days, which is just about the best insurance you can have against tragedy in warmer waters to me.

As far as amenities like you talk about. I was planning on a camper style ac unit, inverter generator on the swim platform (multiple CO detectors inside the cabin of course), Small fridge, and a single or 2 burner electric hotplate for food, coffee, and tea. The thought of a pressurized propane cylinder in a salt water environment freaks me out a bit. The cabin roof will be insulated.

I saw Barry's GT23, but I'm not ready to do this quite yet. To be honest again, I'm not in love with the plans from Bateau, or the speced lamination schedules, after building the FS17. If I did get someone else's hull I think I'd want to rebuild part of it to increase the strength and rigidity. Plus I really want to move away from wood, composites have come down so much here.

 

That's what I got more or less, but there has to be more to it. A barge can't have the same displacement speed as a sailboat or trawler right? What about a pontoon boat? No planing there, but the 20ft pontoon we went scalloping on last year can cruise along at 12mph.

 

For displacement hulls, they would be subject to additional drag. The pontoon is not a displacement hull, so rule dna. Pontoons plane with sufficient power and if the hulls are not deeply immersed.

In theory, if the barge, sail, trawler had similar drag, afaik, they could theoretically all have the same length and the same hull speeds. However, it is more practical to consider like hulls vs each other.

I still think that gt23 would serve you well. It is probably a tad small for four.

Composite foam work is dreadfully slow if you want to do it well. The tangible benefit on the gt23 would be that you could build the house in foam...lighter, get some experience, some r value..

 

Florida is a paradise for anyone looking for unwanted or discarded fiberglass boat hulls.
For a trailerable houseboat, I’d be looking for a tri hull of maybe 24’ to build out.
Keep the structure light if you’re going to move it about, or you’ll pay a penalty in speed and fuel.

 

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