River / House Boat Design Exercise.

Gents I have always liked the idea of a "Houseboat" or call it a "Riverboat"

The idea is that you have your weekend "cottage" on a trailer that you can easily tow.
The boat must be as light as possible.
7.0m long by 2.5m wide (21 x 8 feet)
A displacement hull, good for 6 knots cruising, sheltered waters.
A 20hp fourstroke outboard motor, to punch into the wind.
Flat bottomed so that you can beach easily and keep CG as low as possible.
No dirty stinking bilges.
Lots of floatation - fore and aft = unsinkable.

The boat that got me thinking is the Glen-L Gypsy, I love the interior layout.

https://www.boatdesigns.com/20-Gypsy-trailerable-houseboat/products/168/

Here is my take on the interior with minor changes. Just added 2 lockers for storage either side.
I love the idea of the forward deck where you can sit away from engine noise, obviously it will have to be selfdraining.

My hull is very easily driven 3 hp @ 6 knots @ 2200 kg displacement = 300mm draft. (Freeship 3.1)

So the questions are,
What do you guys think of the hull and accomodation combination?
What do you think of the idea of a 21 foot Riverboat?

Keep in mind she is a "cruiser"

 

I have some little experience with this style of yacht and the upper chine on yours, is just a waste of time, materials and energy, as it doesn't do anything at all for the hull form, so why bother with them. They do save a very modest amount of wetted surface and ease entry angles very slightly, but not enough to warrant them. If you want a second chine, make it do something beneficial for the hull form.

Really small riverboats are hard to do and not have them look like a little Winnebago is parked on a big jon boat. The interior seems serviceable, though cramped, as you'd expect of this length.

A well designed boat like this, could easily be under 2 tons. Positive floatation is possible, though it'll eat up a lot of storage and equipment allocation volume. I also think this set of hull form shapes will not be especially "efficient" compared to other options, though a marginable point considering it's target speed.

 

Thanks PAR
interesting - only a 100 kg less displacement and only 100 watt more power
very little indeed
definately would save a lot of work

 

Lots of fun to do an exercise like this

then of course the ugly BUT BUT BUT's rears it head

1 = the costs (wife will kill you)
2 = the space to build

and last and the worst

3 = a suitable vehicle TO TOW it with AND
4 = the double axle tailer.

boats are fun aren't they

 

Sorry, new thread is more appropriate.

 

Manie: John Welsford is currently drawing a boat exactly like that - the Footloose

http://www.jwboatdesigns.co.nz/index.html

Richard Woods

 

Hi Richard,
I cant find footloose do you have another link perhaps?

 

very well understood and I absolutely agree with you

I just bombed this into CAD - quick and nasty - 3 minutes
so please excuse the lame drawing

But what is interesting is that the "box" doesn't look that bad
The side panels can go up a little to get a better cutting size from 8' x 4' sheets but that may not be necessary anyway.

The galley is now a full 2m which is great!

 

oh and I dropped the curved stern panels they are now straight

 

Just interesting the low power requirements of this type of hull.
2100kgs at 300mm deep and 3000kgs+ at 400mm deep

What I must say for the Freeship figures are that they are more or less in line with what I am experiencing in the real world with my boat.
I did 19 hours on 25 liters at 5 knots average - and total displacement of around 750 kgs on a 5m boat. That's me, booze, 7 days food and 75 liters of fuel

 

John probably doesn't have it online yet as it "hot off the press" but he's sold a few sets of plans so you'll have to contact him direct

Richard Woods

 

Hi Manie. I agree with PAR that the double chine is a tough sell on your boat. It does change the stability a bit. For a trailer boat, I prefer a file bottom boat rather than dead flat. Say about 5 degree deadrise. This flattens the chines, but doesn't change the floor height. It also lets the water drain to the centerline when the boat is cocked on the trailer. It gives you a couple extra inches to fit a bilge pump or some trim ballast, and room to reinforce the keel area. And you get the strength of a fold along the keel. You can bookmatch cut all the pieces to for stitch and glue. I'd probably let the transom drag a bit with a 20 hp. She looks like I would set her for an 8-10hp, unless it is a bumpy river in places. In short, A file bottom will do about 95% of what the double chine would do (admittedly, that's not much). It also gives you an extra degree of freedom you can use during panel layout. You can move the chine a 1/4 inch if it makes it work. I'm a terror when it comes to panel layout and nesting. I like the proportions of the hull.

 

philSweet good points, also good to hear you like the proportions.

What I want to do now over the weekend is to play around and "compress" the design.
The idea is to get the length down to actual sizes, that still means the boat is comfortable but shorter.
From an interior layout point of view I think I can get it to 20' = 6.1m
Once I have done that I will re-visit the hull to try and keep 6 knots at under 2 kw - it will be interesting to see how that works out.

thanks anyway

 

Just for fun.
I doodled around to see what would happen.
This is what I came up with:

1. Aft deck (1m) which will be selfdrainning and a board-cover over the motor to help reduce engine noise.
2. Dinette that folds down to a double bed (2.1m)
3. Galley area (1.4m) big enough for a wash basin and a 2 burner gas stove. Under counter gas fridge.
4. Front self-draining deck (2m) just nice for two deck chairs.

I am confident that you can steer away from the Winnebago look, which is always a worrying thing.

So still within the "Gypsy" look and feel - with a displacement hull.
almost 3000 kgs displacement at 400 mm deep
Still fine with a 20hp fourstroke motor - light on fuel 6 knots cruising
enjoy

 

Here is the DXF for anyone that wants to doodle