Adding vee to cat hulls

This is exactly what I mean; assume Your English is better than mine.

And You are right again about re-sale. To add, any additions/modifications would reduce resale value and will make potential buyer suspicious about purchase.

 

Lots of good comments and all appreciated.

Of course a more intelligent sailor would sell the boat and avoid all this misery but what can I say? What I should do and what I do usually don't match in my experience. It is a weakness of mine, but I would have a hard time selling a faulty boat to an innocent buyer (although my PO had no problem!). Also, as I have rebuilt this beast from bare hulls I have designed in some features that I would not want to be without and are difficult to find on the used market, such as a forward working cockpit.

I considered cutting away the old hull under the addition but, while saving some weight, I would sacrifice the crash compartment that the addition will create. We are contemplating a trip across the N. Pacific in the next few years and apparently there will be a lot of debris from the Japanese tsunami in the way. It would also add work in modifying the bulkheads and fairing the interior

Concerning plywood, that is definitely a bailout option only. My first choice will be foam and Oh at PSS tells me she can get it. My own experience with Diab was Kafkaesque and I would not like to repeat it. It would not bother me too much to use ply as many good boats have been made of the stuff for decades. The problem, as Hakim points out, is finding suitable stuff. I bought a sheet of "marine ply" in Langkawi recently that came with a cool CE stamp and high price tag, but delaminated as soon as I cut it. A piece left out in the rain next to a scrap of plain birch ply virtually exploded while the birch just grew mushrooms. A friend did some boil tests on Thai ply and some of it did quite well. We'll see, hopefully a non-issue if I can get foam.

Hakim, do you ever make it out to Rebak? My boat is in slip A-1 as you enter the marina on the ferry. We are in California working now but will be back in mid-August. Stop by for a cold one if you are in the neighborhood.

 

That's brokers job to sell boats to innocent buyers. They do it every day

 

It looks as if your preferences show you the way:
- No selling ( I also only would do it if right after I will leave the continent...)
- No excessive time and effort invested.

Your conclusion is maybe a little heavier than it could be. On the other hand: If one is planning to cross an ocean it does not really matter if one arrives two days later or not.

As you mention Rebak:
- A while ago I met Jon and his friend (forgot the name) who were building there -on the dry- on their Schionning. Maybe he is still around and can give advice about material.
- On THIS side of the island I know that JG boat yard has a stack of AIREX foam (100 kg/m3) which they do not need - it is left from a previous project. You may be interested.
- Material logistics to Rebak can be difficult at times. There is also an option to build in Temmoyong (next to the container terminal); only hauling there is more expensive as they have no travel-lift and use mobile cranes.
- If you happen to meet a 'Rico' who offers you his service: shoot him in his back; or he will shoot YOU

 

This is likely to be stock from our 36' cat design/project; they planned to build it in foam and now building it in Hexacor. That project is moving damned slow... since 2007.

 

Yep: When ever I go there I see three or four guys fiddling around, and no supervisor to be seen... One of these guys recently joined ME because he felt under-challenged there
You can't blame the guys; it is rather a management issue - like so often

 

Err, guys, "ADDING VEE TO CAT HULLS" please !

 

That's not a rocket science; we have already looked at 3 options:
1. O+>
2. O-)+>
3. O to $$$ and C>

 

Sorry. You are right

 

Regarding this; Kosan makes a marine epoxy that is cheap and widely available in Langkawi. I was told once that this was "formulated for high humidity" and therefore suited to the tropics. However, as I listened to this my ******** meter crept dangerously into the red. I have used it for repairs interior work and it looks and behaves like epoxy, but it smells like turpentine. Anyone have any data on this stuff?

Mike

 

See my PM

 

I am a Master Marine Electrician, but on occasion I am able to convince the Naval architects to let me try and design Catamaran hulls.

And this is what I found playing around with the 65 ft sailing Catamaran hulls:

There are a lot to hull shapes, but many shapes will meet certain requirements, meaning displacement, semi-displacement or planing, for example.

The hull design is very vessel specific, in terms of what it has to do, and there can be several choices which are close in performance, and will require tank testing to arrive at the final shape.

So for the 65 ft Cat the starting point was a displacement hull. From here I had to go down the list of customer requirements. For example, point well with no dagger boards, and could also be beached without damage.

But, for me the hull newbie, I was able to provide a nice fair (constant curvature surface) rounded V shape which would point well without a board, and was able to remain on its lines, perhaps move 3 inches down, from empty to full load.

So what was fascinating was the ability to manage load capacity per the hull shape by focusing on how the shape influenced rate of displacement with sinkage.

Meaning I could guarantee the bridge deck height over the full operating load of the vessel without too much difficulty.

Also, interesting for me because for many reasons I would like to see more transverse frames closer together of thinner material to support machinery and floors and just about everything else. Than broadly spaced heavier frames. So if you move into the area of what would be considered thin frame scantlings, I could maintain strength, even though it was not directly addressed by ISO rules.

Fun stuff.

Mark

 

I am a master boat builder but on occasion my customers allow me to build a boat the way I learned it once.

Nice to see your professional satisfaction, but we talk here about a different boat I was told...

 

Mike,

the boat in the picture also suffered from slamming, they added a strip of plywood to the bottom of the hull forward of the keel and glassed it over. Aparentely it helped.


Does not look nice but...

 

Simon,

Thanks. It's hard to tell from the photo, but it looks like a single chine with a flat bottom and very little rocker? No wonder it pounded! Nice to know I have company. My fix will be quite a bit more involved but I'm hoping the results will be worth it. I plan of having this boat for a long time. Here's a screen grab of what I am aiming for. Old hull on the left, modified on the right.

Mike