River / House Boat Design Exercise.

Hi Richard, I did contact John - he will be back at the end of the month from the Tasmania Wooden Boat Festival
He will send me a study drawing of Footloose - it is going to be very interesting to see his take on this subject

Will keep you guys posted

 

Just a nice pic of a motorwell

 

You might consider adding a shallow, long, box keel that serves as tankage. . Water tank of say 150 liter. The weight would be centerlined and down low , as she empties your trim wouldnt suffer. The keel would also give other benifits ..directional control, a good skid pad if you must winch your micro ashore or partitioned into grey or black tanks.

 

With this set of drawings I did the cabin sides and roof all in Freeship - just to ensure that everything is in the same scale.
So the boat is now 6.5m o/all x 2.5 wide and 2.0m total height
All panels cut from standard sheets that are 1.2m wide (4'0 wide)
this way I could build it in my garage in 2 sections and then later just bond the bow section onto the rest.

I like this weekend cottage - maybe one day I get crazy and build it
if you ever want to see a woman have a heart attack - I'll invite you over when I announce the news to my wife

So in between spending WAAAYYYYY to much time drawing on the computer I am doing my bulb and will start with the mast - soon!!
I might need the space

 

Strokes for folks - you decide
this for sale in South Africa

http://www.houseboatforsale.co.za/?gclid=CIfuw-n2qbUCFaTMtAodUCkAXA

???? fugly
???? Winnebago

 

Yes . quite ugly Manie.
Useful though .....

 

I quite like the look of this one .
It could carry quite a load for its length too.

I don`t think a boat like this would be all that expensive to build either.

 

I suggest you chop the crews legs off at the knees, then put a bilge into the micro !!!


Also you will get a lower profile house and more headroom if you put extra...extreme, camber into the house roof.

http:// pic hosting

 

Displacement at the indicated waterline = 3200 kg = plenty

 

Three and a half tons on that short a LWL, with that much belly will make a massive wave train and efficiency wouldn't be a term to describe it.

 

Your`e right there Paul , I think this hull would benefit greatly if it were stretched out a little ( lot ).

Being a trailer boat I guess you have to set limits to length etc...
I think as a trailerable , you could get by with less displacement.

Slower is usually better too , for this kind of boat.

 

I am quoting figures as calculated by Freeship 3.1
What I have found on my present boat is that the Freeship calculations were reasonably accurate @ 5 knots and 5hp @ 750kg

So am very aware of what you are saying AND I KNOW that you have 100% more knowledge and experience than I have, so the problem is - a small boat like this, built lightly, will possibilly be around 1500 kg, by the time you have batteries, water, food, fuel, 4 people on board the 2500 kg mark comes up very quickly.

I dont think it is prudent to be ambitious and design "light" I have seen failure after failure because the boats invariabily hit the water much heavier than "designed"
So my thinking is to be on the safe side and say a maximum of 3000 kg is probably "safe" with a light ship condition of 2500kg and then a cruising speed of 6 knots.

So the problem is - what do you do with a 6.5m x 2.4m boat - full up 3000 kg - to minimise drag?
There are 3 things you can play with=
Bow up or down
Stern up or down
Draft deeper or shallower

The one thing that is difficult to run away from is the 1500 kgs - as a plywood stitch and glue - epoxy and glass construction, it has it's limitations as well.

Add to that another 1000kgs for 4 people, and the long list of other things, it is not that bad either.

The enemy is and was always load - or rather overloading - so is it not better to cater for that, and with a bit of luck you run "light"

PAR thanks for your input - I alwyas take not of what you write.

 

I think that is part of the " art " in boat design.

 

Light can be strong, though it takes clever use of techniques and material selections. I too think this design needs to be drawn out length wise a bit, which will ease it's burdensome shape considerably, thus improve efficiency. I also think the Boat Fan version of the topsides, is more palatable aesthetically, though using a bunch of roof crown can visually lower the cabin impact and permit lower freeboard too.

This is a classic novice engineering mistake and one that will cost you in build time, complexity, materials use, etc., all just to have a reserve of some sort, for something that may never be needed. The is the DC-3 engineering approach - build it way over what it needs to be and you can beat the hell out of it if necessary. The same aircraft with modern materials and techniques would be half as heavy (less material to buy) and twice as fast, with the same power.

My point is you can design for every eventuality (which may never happen) or heavy duty, just in case, but you have to pay for this in build time, material costs and operational inefficiency, because of the extra burden the yacht has to bare. This is hefty price for a houseboat, which will never likely see much more than, modest wind strengths and a mild chop.

 

Manie, did you see pages 8 and 9 of this thread? the "shantyboat" of post 117 in particular?

http://www.boatdesign.net/forums/boat-design/retirement-houseboat-floating-home-23987-8.html