http://wharram.com/tiki21.html

I have a rig like this:

http://www.wharram.eu/photos/index....ge=Tiki%2021%20Dan%20Swan%20NC%20USA.jpg

And I'm thinking of going to a rig like this:

http://www.wharram.eu/photos/index..../Tiki-21&image=2005maragojipe114.jpg

Comments?

Why do you want to change the rig?

I'm not really sure that I do. I have difficulty going to weather with the gaff. . .wait! Didn't I say that already?

The decking has rotted away. When I bought it, the deck had been rebuilt but not to the specs of the builder. Now that must be replaced.

Also, the rudders, which are made of plywood, need some work. One is damaged beyond repair and I was thinking of edge gluing some pine and covering with epoxy/cloth as a replacement.

The gaff rig is a good rig for a cruiser in my opinion. Not superior to windward, but good enough. On a reach it is superior. I would not have gone to a bermuda rig on a Tiki21, but kept to Wharrams design. But surely there are Wharram e-groups that knows loads about this? What I would have asked myself is "how much do I beat to windward". Upwind is the only course the bermuda sloop rig is any better, and marginal at that.

Plywood not sealed properly will rot, fact of life unfortunately.

You want to build a new rudder? Edge glued pine.. How about proper Western Red Cedar edge glued with epoxy/thickened epoxy and glassed over? Rot resistant, light and strong.
How are you planning to shape the rudder? With a handplane, a router, a CNC router, beltsander or??
I have broken several plywood foils on old tornados. Even one rudder that was glassed with heavy tri-axial glass on both sides eventually broke when the glass sheared off the plywood. That was while we were experimenting with mega-rake on the mast.. I have never had a foil done with edge glued planks fail. I am sure one of those can break as well, especially if it is not done properly. But not yet.. *knock on wood*

Do you have any pictures of the foils and the rotted areas?

I don't have any pictures at the moment or the ability to upload them. I suppose that would be the first problem that needs solving.

The biggest problem here is neglect. I haven't touched this boat since buying the Blade three years ago. The remaining rudder has mushrooms growing out of it. The other was broken when it got caught up in the timbers of a dock in rough weather (don't ask).

Most of the work will be by hand or with small power tools. There isn't much shape to the rudders, none at all except the leading and trailing edges are rounded over. The most serious problem is the deck. As designed, this is in three separate pieces and is merely suspended at it's perimeter. The baring surfaces are about an inch wide (2.5 cm). As this carries the live weight of the crew, a small outboard and some deck cargo, I'm a little dubious. I don't want to get half way to Dry Tortuga and have the whole thing collapse! Also, the outboard cavitates easily, to the point that it is all but usless in a seaway.

I was thinking about pine for the rudders, simply because it is readily available. The big worry is the decking. Since it is basically wood on wood, water collects constantly and chafing is not just evitable, but constant.

I've found a number of e-sites since the first posting and am in the process of going through them.

I would re-do it according to the plans, if you have them. It might be that the boat is not done to the plans, I dont know but it is a possibility. Tiki21s have sailed around the world so I dont think there is anything wrong with the design.

I know a couple of strategies to stop cavitation, all with their own risks. One is to lower the outboard, with the risk of swamping it. Either build a custom holder or a "sled" that is lowered when motoring. You could also get an engine with a longer neck to the propeller.

Hand tools to repair/rebuild a Tiki21 sounds good. A battery drill is nice of course, but a good handsaw is almost as fast to use and more precise. A japanese pull-saw is much more fun to use than any electric saw

When I was thinking about Japanese hand saws 25 years ago they were very hard to come by and would have been accompanied by a brace and bit. To make a long story short, I opted for electric and that's what I meant by "hand tools": Bosch jig saw, makita circular saw and 1/4" drill, plus a Hitachi table saw. There are of course the rasps, files and coping saws that require a little muscle.

I bought the boat complete and it was built mostly to specs.* The decking is not to spec, neither are the hatch covers. The biggest problem with the decking is that a hole was cut in it to accomodate the outboard. That problem would be resolved by mounting a bracket aft of the rear beam. But, that solution presents problems in turn. Everything is a compromise.

*I actually bought a set of plans, #789, and was ready to place my first materials order. But, I thought to make one more check of the Wharram website and found a Tiki 21, ready to sail, with passable trailer and like new Tohatsu 4 cycle 5 hp outboard. The price was, to the penny, what I had calculated for material; ABSENT outboard and trailer! The decision was obvious and I bought this boat rather than building.

Just got this from Tami,thanks again.
http://tiki21element.blogspot.com/search?q=


Wharram catamarans offer amazing versatitlity.

Pete,
Plywood is often used to make rudders and c/bs because people can get it easily and its layers give you a good indication when shaping it. However plywood is not the best material for this application because it does not like the rolling stresses that the rudders and C/Bs experience.
If using ply you really should ensure the laminate takes all the load and the ply is just acting as a core.

When considering the strength to weight ratio laminating strips of timber will form a much more durable rudder.
Having said this I would not use pine.
Western red cedar with a hardwood leading and trailing edge would be my preference.

As you are taking this boat off shore I would still not skimp on the laminate. In a boat where I wanted to be pretty sure the blade was going to stand up to the rough stuff I'd also laminate at least 3 layer of uni carbon (0 and +_ 45deg) each side under a layer of plain weave glass.

Unlike plain weave carbon, Uni carbon is not very expensive and stronger in the one direction.

If carbon was not obtainable then I'd use UNI glass but just use more of it. If I couldn't get UNI glass I'd use plain weave in that order (strongest to weakest).

This is just how I'd approach the problem.

Good luck with the restoration. It would be great to see some pics and see the work as it progresses.

Regards,
Phill

I'll stay with the plans as much as possible and try to make a start when I get back from Kelly Park next weekend. But keeping my motto in mind, be aware that I'll be missing three days worth of naps.