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bodhi02 · 02-06-2011, 04:08

I am one of those guilty "lurkers" finally coming out of the dark.
So here is my plan and thoughts...
I will be retiring in about 7 years, and will start building a catamaran next year with plans to complete it about 1 year before retirement so I can get all the kinks worked out before starting to cruise. I am pretty well settled on the Wharram Tiki 38, as it is definitely home-buildable, open-ocean worthy, and can be completely built, then moved to the water in 3 pieces for final assembly just before launch. I have no concerns about my ability to build or sail this vessel, and will be cruising the US South-east coast, El Caribe, and the South Pacific, doing alot of diving and fishing, so the Tiki 38 really should be just about perfect.
However, I would like a little better tacking, turning, and windward ability than they seem to have. So my thoughts are to extend the hulls by 2 feet, the beam by 1 foot (thus maintaing the current length/beam ration), leave off the fixed LAR keels and instead build kick-back centerboards into each hull, and increase the sail area by about 15%.
Using the centerboard in the windward hull only should eliminate the problem that schooner and ketch rigs tend to have when coupled with a centerboard in that they are difficult to counter the weather helm due to the widely dispersed sail area "pivoting" the boat around the centerboard (thus the reason for them having full keels). By using only the windward board, the sail effort will be "pulling" the board through the water rather than "pushing" it, which is inherently much more stable.
I will also be building with a lot of end-grain balsa core and foam core in order to minimize weight and increase performance.
So, what do those of you with some experience with either the Wharram Tiki's or ketch/schooner rigs think of my ideas for increasing the performance? I know that James Wharram is not a big fan of people tweaking his designs, and generally will not respond or give his blessing to any changes. I can't blame him for that, as today's litigenous society is always looking for a scapegoat if something doesn't quite work out.
Any thoughts, comments, or suggestions will be greatly appreciated.
Thanks,

Bruce

Woodchuck · 02-06-2011, 04:18

Try out the Wharram Builders and Friends website. Someone will be able to tell you whether this is feasible or not. The tiki 38 is great for what it is designed for. Trying to make it into something else sounds like a bad idea to me.

**boatman61** · 02-06-2011, 04:34

I'd tend to agree with the above...
my tack is... if it was feasable the Wharram Design Team would have done it... they tried a similar thing with the Pahi's at the bows to try and improve the performance to windward... I believe they stopped doing it due to problems... failures/leaks etc in the daggerboard areas...
I'm no expert but seems to me your trying to fit something meant for a rigid hull set up into a flexi hull set up... somethings gonna give..
But I could well be wrong...

won't be the first time....

imagine2frolic · 02-06-2011, 04:49

A fella looking into building a Wharram wrote Wharram. Asking about designing a more conventional bridgedeck. He wrote back saying if had wanted a bridgedeck he would've designed one. You may have better luck on the Wharram site though as advised........i2f

Wand · 02-06-2011, 04:53

Quote:

Originally Posted by bodhi02

I have no concerns about my ability to build or sail this vessel, and will be cruising the US South-east coast, El Caribe, and the South Pacific, doing alot of diving and fishing, so the Tiki 38 really should be just about perfect. However, I would like a little better tacking, turning, and windward ability than they seem to have.

If you've found a boat which is "just about perfect" for your needs, watcha doin messin? Everyone wants a little better tackin and turnin and performance beatin but, if you're planning some long journeys with fishin n divin, those things will hardly be important to you.

If you like to fiddle and play for the heck of it (like I do), go ahead and have some fun. But if you're building a vessel to cross seas, and want sleep at night, I'd stick to the plan to the milimetre.

anjou · 02-06-2011, 05:01

Deviating from plans will cost you more time and money, and whilst your revision may appear simple on paper, you may well run into practicality issues.

Move one thing by an inch at the bow and by the time you get to the stern its become a foot and it then clashes with something you didnt initially invisage. Ive been there and done it.

As regards Wharram not liking plans changing, you can bet your boots hes already contemplated what you propose and I know from experiance how annoying and frustrating it is when a client deviates from the objective and has little to do with litigation.
'But Amy, your getting paid to move this doorway over there' does little for my pride in the job. We prefer to do it once and do it right, not a series of mistakes and patches after.

Mark Johnson · 02-06-2011, 05:07

Quote:

Originally Posted by boatman61

I'd tend to agree with the above...
my tack is... if it was feasable the Wharram Design Team would have done it... they tried a similar thing with the Pahi's at the bows to try and improve the performance to windward... I believe they stopped doing it due to problems... failures/leaks etc in the daggerboard areas...
I'm no expert but seems to me your trying to fit something meant for a rigid hull set up into a flexi hull set up... somethings gonna give..
But I could well be wrong...

won't be the first time....

AGREED!

BTW... My Wharram did in fact sideslip going to windward more than I'd like, but it did "get there" nonetheless. Tacking is not a problem at all. I'd just sheet in the jib tight, throw the helm over, backwind the jib, and set off on the new tack. It did often stop the boat momentarily, but I didn't have to "pull" the jib across... it almost tacked itself.

Mark

**boatman61** · 02-06-2011, 05:20

Quote:

Originally Posted by Mark Johnson

AGREED!

BTW... My Wharram did in fact sideslip going to windward more than I'd like, but it did "get there" nonetheless. Tacking is not a problem at all. I'd just sheet in the jib tight, throw the helm over, backwind the jib, and set off on the new tack. It did often stop the boat momentarily, but I didn't have to "pull" the jib across... it almost tacked itself.

Mark

And.... Marks Wharram was the old 'original polynesian' design... much heavier...
I've owned a Tiki 21 and a Tiki 26.... they are a much more nimble beast... never ever got caught in the irons.... and... if ever you do... just put opposite helm on and you'll reverse out of it and away on the new tack..
this was something I used to do on purpose to manouver in tight quarters under sail... nearly as good as having twin props....

cat man do · 02-06-2011, 05:31

So why not just build this?

Mike Waller Yacht Design - Coral Cove 40 Catamaran - Boat plan for amateur builders

**boatman61** · 02-06-2011, 05:56

Maybe because the underside sucks....

bodhi02 · 02-06-2011, 06:01

Cat Man Do,
Interesting boat. In my year of surfing/searching through the internet, somehow I never came across the Waller designs before. However, the same problem exists in that I would have to do epoxy and paint work on the bridgedeck and hulls at the water, and the nearest boatyard that can handle a boat that size is a good hour away from my house. If I was going to do that, there are many other designs I would build instead, such as the farrier F-41, Schionning Cosmos 1160, Woods Mirage, etc...
Additionally the Waller design has those under bridgedeck steps for the lateral bunks, which I don't like because of the slamming inherent in that design.
However, thanks for the thought. Much appreciated.