It's getting cold- must be boatbuilding season

[bljones]

Hello all.

Objectively, i know three things.
1. Owning a boat is not rational.
2. Building a boat is even less rational
3. Least rational is designing the boat and THEN building it.

Where do I sign up?



Here's the deal:
SWMBO and I love our current smallish fiberglass monohull sailboat. We also enjoy our ply and mahogany motorcruiser. We love the dock where we spend our summers. But...

There's always a but, isn't there?

We want more space in one package, without having to leave our dock because we exceed the max length. 26 feet is the magic number. It's great to have living space on two boats in one location, but when the dock is in our wake, we can't take both boats with us. Well, we could, but that is an absolutely overly complicated and utterly stupid solution, even for me.

So, last weekend, deep into a six pack of Neustadt Springs 10W30, I began planning, and sketching and thinking and next thing I know I realize what we really need is a catamaran!
Right then, is there a cat that meets our length spec?
The Catalac 8M might just do it, but $30K+ is big dosh.
Or a Heavenly Twins... rare on this side of the big water. A Hirondelle is too cramped...

So, we need to build one!

Okay, let's cost this out, and then let's double it, and then let's work up a schedule and then triple it and then...

and then I bought a parts boat. Now I'm committed.

So I hope you all don't mind stupid questions, and the endless enthusiasm of a novice who doesn't know or care that this is a really really bad idea.


bl.

[troy2000]

Uh-oh. And another one bites the dust....

Building your own boat is a supremely irrational goal, but one that must be approached quite rationally if it is to succeed. Good luck, and keep us posted.

[Manie B]

Hi and welcome to the club
please post pics
it help much more than you think
also of your "old" boats and the jetty and "waters"

[bljones]

Thanks for the welcome.

Here's the plan- A Dory hulled cat with twin skegs on each hull.
7.75 M LOA
6.85 M LWL
4.5 M Beam
3.0 M between hull centerlines

Primarily a boat for a couple, with a queen size berth forward, an occasional single in the aft third of the port hull, and a salon dinette that will convert to a double.

Stitch and epoxy "devil-design" construction (666- six bulkheads, 6 mm ply, 6 oz fiberglass cloth )

I am completely incapable of working in cad, or any of the hull design programs I optimistically loaded onto my computer, so I have sweated it out with pencil and paper on the drawing board.

First version:


Better version:







Pics of our current boats, my low-buck projects and the dinghy I designed and built two seasons ago are on my blog, linked in my signature.

[lewisboats]

I think I would bump most of that ply to 9mm rather than 6mm...that's a big boat and lots of easy curves with open spans of unsupported area. One good bump on the corner of the dock in the middle of a span gets one good crack in the ply (momentum + wind = a lot to stop)

[bljones]

Good thinking, Lewis. I am trying to keep the weight from getting out of control. Maybe the outer walls of the hulls in 9 mm and the inners 6mm?

[lewisboats]

Sounds better. You could also go with meranti on the outside and Occume on the inside. Be the same weight wise as meranti 9mm on the outside and 6mm on the inside.

[yipster]

Working with meters is good, so is drawing in more body's,arms and legs for size

[Silver Raven]

Originally Posted by bljones

Good thinking, Lewis. I am trying to keep the weight from getting out of control. Maybe the outer walls of the hulls in 9 mm and the inners 6mm?

G'day Canuck. COLD - ah - is that why I moved to the tropical parts of Far North Australia. Yes - now I do remember. Last time I sailed on Lake Ontario was 1955 with my Uncle on an Ice Boat out of Kingston. Sailed up to Toronto & back. They owned the Ice Works way back then.

If we can/did build a 40' cat back in 1967 weighing 5300 lbs total - me thinks (read as I'm totally positive) you can build a 25' to 30' cat - with top quality marine ply plus a 6oz glass cloth inside & outside c/w epoxy resin using 4 mm ply. You need 9mm ply for an ice-breaker not a sailing catamaran. I thought sail boats were ment to sail around obstructions not through them. OH & said cat lasted for over 40 years in good working order without any repair at all, before we hit a whale & needed a new bow - back to the front collision bulkhead - but we did sail 300 miles home with water in that hull.

I still think you should do a lot of weight research before selecting the hull shape/volume needed. I've just spent over 2 years trying to get my personal (not yours though) weight requirements for safe sailing - down to 3000ks or under in gross total. Found that very hard to do though. You'll need less safety gear thus less weight but - anything & everything adds up ever so fast. Average people - the food they need - over 3 or 4 days - the water (& other liquids) - engine & fuel - anchoring gear - safety equipment - personal gear, etc, etc, all add up real quick.

The engine weight alone is a very interesting discussion for sure. Thrust vs hp vs weight vs safety vs fuel consumption factors all take some time to consider & are all very important to the well being & safety & enjoyment of the project as a whole.

I like where you have positioned your engine. Nice & away from the transom!

Enjoy your task. Ciao, james

[bljones]

Thanks james, for the input, the advice and the O/B positioning kudos!