With trepedation….

…I quietly announce the ‘pretty much’ final design for my boat.

Mastodon 21′ by Daniel Powell Conti

Everything was well and good with my previous final design, so as I mentioned before I was doing some 3D modelling to put up a picture for your entertainment. It was then that I realised a horrible design flaw.

It looked shit.

I am not going to spend thousands of pounds on a boat that doesn’t look awesome. I realised too late that my final design necessity was a cool looking boat. The problem was that the accomodation hull was too tall and fat. It looked like a supermodel and her retarded sister trussed together and passed off as a princess. To put it nicely.

So this is the newer, sleeker design. Hopefully it will actually look like one boat instead of two random ones bolted together. Click on the picture for higher resolution.

image

The vitalstastics

Lee hull (with the mast)
Waterline: 21′
Beam at waterline: 1′
Displacement: 68kg

Windward hull (accomodation)
Waterline: 21′
Beam at waterline: 2′
Displacement: 136kg

Centre to centre beam: 10′

Hull displacement: approx 204kg
Draft: 2″

This is a ‘weight to windward’ design of pacific proa, giving greater stability than a more conventional ‘flying’ design. I will talk a little about the important changes. The crossbeams, the hulls length, the mast step, and the accomodation.

I have four crossbeams instead of the more conventional two, generally something more often seen on catamaran. This may be a case of structural overbuilding but I want to feel safe in this thing. I feel that with a hull made of 4mm marine ply I could use a little extra support for the extremeties of the boat wich would otherwise stick 7′ free from any lateral support. The four beams will have strong internal support built into the bulkhead below as well as longitudinal support from one crossbeam to another. There are other advantages too. I am now able to build the rudders closer to the end of the hull, increasing their leverage. I will also be able to string trampoline mesh between the outer and inner crossbeams, doubling the available deck area.

I have increased the length of the hulls as well as making the ama and vaka (main and outrigger) the same length. This was after I saw a similar design called ‘Ping Pong’ by Terho Halme. It has equal length hulls and sails just fine. It solves several problems for me. The problem I was having with the ‘weight to windward’ design was not having enough space or displacement in the windward accomodation hull. Having a 21′ windward hull solves it nicely. I have not gone back on my ‘easy to build’ principle either. By sacrificing a bit of inside space the hull can be made to be 2′ high with an additional 1′ cabin top. This still leaves space for two to sleep, head to head instead of next to each other. The space will allow two to sit and face each other with space to cook or play chess inbetween when they are not sleeping. However generally, while sailing, two crew members would not be taking sleeping shifts at the same time. If moored or at anchor there is space on the 14 sq ft deck to pitch a tent.

I have chosen to step the mast to the crossbeams rather than into a hull. I want a mostly freestanding mast for ease of manufacture. As I said in a previous post, stepping the mast inside the hull raises problems that I can just avoid. Furthermore, having the mast on the crossbeams allows me to move it, repair it and generally be able to access any part of it without having to mess with an integral part of the boats structure. It also makes it easier to earth the mast incase of a thunder storm, I can just trail some copper wire in the sea.

The unloaded displacement is 204kg for 2″ draft. Day tripping with three or four people would be around the maximum displacement of 520kg which would give a draft of about 6″. Adequate for smooth seas.

The only real complexities are the angled, three chine hulls. I feel they are quite necessary to avoid slamming into waves at high speeds so they stay. Because the boat has no rocker so it is a manageable level of complexity.

I have a boat designed. It is simple yet elegant and will look sweet as when decked out in bright red paint. Now I just have to think of the…cost…
COST:
14 x (4mm x 1.2 x 2.4) marine ply = GBP 252
60kg epoxy = GBP 624
27m sq of CSM fibreglass 300gsm = GBP 24
40m sq of 300gsm woven glass fabric = GBP 52
Paint plus antifouling = GBP 100-200

total cost of hull = GBP 1052

Then all I have is estimates for the other costs.
Workshop and tool hire GBP 800 (?)
Aluminium poles GBP 80 (?)
Sail GBP 200 (?)
Rope GBP 100 (?)

Estimated bild time: 240 hours

Assuming my estimates are sound the minimum cost will be around GBP 2232. Knowing from the outset that there is a snowballs chance in hell of sticking to the minimum budget I am giving myself a budget of GBP 3000 to complete the project.

That seems like a lot of money so I thought of other stuff I could buy for three grand that would help me enjoy travelling around New Zealand.
An old car and 6 months of petrol and insurance.
An old monohull sailboat.
A 14′ racing catamaran.
A cheap Armani suit. (Wait, that wouldn’t help at all)

So to hell with common sense!

 

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