Casey,
I can't speak authoritatively on a triple rudder setup but I can envision a new level of rigging aggravation. Looking at your previous pictures of the rudder, I think you need to get a second set of gudgeon and pintles at the bottom of the rudder control head. I'd imagine the torque on a single set is considerable. I've got a CLC Triple and Sailrig outfitted with a very large homebrew rudder. I attached it using two sets of strap style gudgeons from JLite. Two bolts replace the pintles. Each gudgeon is attached using four #8 1" panhead screws. This attachment may be easier on the Triple than your boat because the stern is nearly vertical but I definitely think a second attachment point is the way to go. I will try to get some pics and post them.
Dusty
Casey, I had the same thought as Dusty. The torques on a high-aspect rudder like yours, on a multi-hull, are enormous. Your rudder mount is in effect like a dinghy rudder that is missing the bottom gudgeon and pintle. A single narrow hinge made of sheet metal at the top is being asked to handle all that twisting force. Because of the short hinge, you are asking it to take 500% more force than a Hobie rudder mount, but the Hobie is 500% stronger (high strength alloy casting).
Hi, with all the talk of pintles and gudgeons I thought I'd throw in this tip I just used to create a rudder assembly for my sailing canoe. The idea is attributed to Wharram, its one of those 'OMG thats cool - why didn't I think of that' ideas. An incredibly strong and frictionless rudder hinge can be made by simply drilling a row of holes along two straight edges (rounded) and lashing in a 'figure 8'. Unbeleivably simple, strong and smooth - (and cheap too). Here is a pic of a rudder on a Wharram cat, but you have to squint to see the lashing...
I made my own version on a much smaller scale with about a dozen 1/4" holes in a continuous row. The pic does not help understand the lashing - I started with a stopper knot, feed rope through top hole in rudder, then pass it back between rudder and mount, then back through mount... Each time it passes between the rudder and mount, looking from 'above' it traces a figure 8 path. The rope doesn't really flex, it just rolls.
Your problem is how to come up with a mount suitable for a kayak - glue a piece of wood to the stern to create a (near) vertical mount? Perhaps you could leave the main hull and rudder alone and do this on the amas? The pull-up pull-down mechanism could be copied from your exisitng rudder? but how to rig this (and steering) on the amas ???
Anyway I was just keen to share this very cool idea.
regards, Dave P
Wow, that really is a cool idea! thx Dave, I never would have thought of it.
Back again - with further thoughts on rudder up-down mechanisms. In my searching I found this just the other day: http://www.dotan.com/ - yep another 'thats cool' idea. On this page the animations illustrate just how nicely this works: http://www.dotan.com/video/
You could buy a couple of these to hang off your amas, but we have all seen the standard of your wood working skills in the photos above. These links:
http://www.dotan.com/construction/ and http://www.dotan.com/adjustment/
give all the clues necessary for a craftsman like you to whip up a couple from okume scraps and epoxy - with Wharram hinges of course!
Then you can tell me how you did it ;-) I so want this set up on my canoe sailer.
Waiting expectantly, Dave P
Dave P
Interesting ideas.
I am thinking of making an end cap for my boat out of carbon fiber or fiberglass that modifies the stern shape to vertical and incorporates the rudder mounts into it. This end cap would be attached using through bolts so it could be removed for normal kayaking. I think that this is pretty much the only choice I have, short of sawing off the back part of my boat.
Hi Casey
if you could figure a way to get rudders on the amas with steering and up/down mechanism - then you could do mods to the amas, which could be permanent, and leave the kayak hull and rudder as standard. On paddling days you have a standard kayak setup, on sailing days the suitable rudders are with the amas.
Surely beach cats have solved the problem of 2 rudders with up/down and steering - Dotan sure has - but there might be some easier systems to fabricate from sticks and strings without getting too messy.
Why not something like: Stern of each ama with wood piece glassed on to create vertical. Rudder on each ama linked with a cross arm (just behind rear aka?) and a tiller like the one you have connected to (say) the left rudder. String pull-up system, gravity down (weighted rudders?) or string pull down. Strings routed foward along amas to foward aka, around small pulleys (or dumbsheaves), meeting right in front of you at cleat(s)...
Casey, your idea of modifying the stern of the center hull sounds really good to me. If I had your slightly amazing skills as a builder, that's what I would do.
As for the options (rudders on amas, etc.): I would rather have one rudder than two or three. My Hobie cat has two, but it adds complexity, cost, weight.
I suspect that the only reason it and other catamarans have two is that it was designed to lift one hull out of the water, so they had no choice. Your trimaran doesn't have that issue. (Does it?)
We do have one or two professional boat designers with multi-hull design/build/sail/cruise experience hanging around this forum, so everything I say is cancelled if one of them chimes in!
Camper,
I came to the same conclusion that cats have two rudders because one hull gets lifted. Plus I got an email from John H. stating that the best way to go is to work with just the center rudder. He says that rudders mounted on the amas would be too far forward to effectively help turn the boat.
I ordered the carbon fiber and epoxy today and will post my progress once I get to work.
As a sailor, a sea kayaker, and about to build a Skerry, I humbly submit the only problem you have is your single point of attachment for the rudder. No sailboat will have one attachment point for the rudder, otherwise it's doomed to fail. Klepper has been manufacturing sailing and rudder rigs for their inflatable kayaks for decades and they always have two hinges (pintles and gudgeons). Your stern is not all that different from the Skerry. Maybe you could fabricate your own version. Here's a link to a Klepper Ebay posting for a rudder assembly. All you need to figure out is two points of attachment vs. your single point. With your building skills, should be easy. All that carbon fiber and modification may well be unnecessary. Here's the link:
http://cgi.ebay.com/Klepper-Kayak-Rudder-Assembly-Seakayak_W0QQitemZ230307112566QQcategoryZ36122QQcmdZViewItem
Y’might take a look at how the CLC Skerry rudder and stern is set up. You could do that with your existing setup by simply adding another pintle and gudgeon further down on your stern and make a Skerry style kick-up rudder assembly. Use a long rudder pin similar to the Hobie setups instead of individual pintles to avoid losing the rudder under sail. You’ve already set up that cool push/pull tiller system just like the one used for the Skerry. No need to fabricate a new stern. Maybe even take some of the cedar strips leftover from your kayak build and continue the strip lines from the hull into a laminated cedar strip rudder assembly inside of which you’ve got your drop down rudder. That way, the whole assembly would look integrated, not added on. Just a couple of thoughts. Occam’s Razor approach.
Casey, my understanding is your plan is this:
1. You plan to solve the problem by increasing the effectiveness of the rudder mount, by increasing the effective length of the hinge. You will do this by positioning one gudgeon (or, the lowest "gudgeon" of a single, long hinge) much lower on the sternpost.
2. But that in so doing, you wish to keep the hinge vertical (for various good reasons, which aren't relevant here.)
3. If you simply put the lowest gudgeon of the -- now much longer-- hinge to the stern, the hinge wouldn't be vertical, because at present the sternpost is angled.
4. So, you plan to first modify the shape of the stern to bring it vertical.
If my understanding is correct, then I agree, and JimKoz may not have understood why you plan to modify the stern first.
Camper,
You have it right.
I thought of doing a skerry style rudder, but since this boat is a kayak, there is almost no freeboard. That means that a skerry style rudder box would be in the water creating a lot of drag. As it is, the box in my current set up will a lot of times be in the water when there are larger swells.
Also, I have no leftover wood from building the kayak or the sailrig. I used the leftover strips on the ama decks and was very efficient in my use of plywood for the rest.
Thanks everyone for their continued advice, I will keep my mind open to any suggestions, at least until I actually find a solution that works!
Have you considered adding stays to the amas? It seems like a lot of canvas for the mast step
There are stays that attache to the akas. They are the same color as the rest of the lines so they might not be so obvious in the photos I posted.
Casey,
Saw your web site and the boat looks quite finished.Beautiful finish job, I wish my stuff was remotely comparable.
I am trying to find someone close to Texas so I can see a finished boat and have a little discussion. Are you anywhere close?
Marc
Marc,
I grew up in Dallas, but I now live in Seattle, which is a bit farther than you want to go I am thinking.
I had my rig out this past weekend and thought I would share the results. The carbon fiber end cap I built to mount the rudder is working well, and it seems like my rudder problems are done. Also, I was very pleased by the way the whole rig performed in some very nasty conditions. After I was on the water, the wind picked up to about 20+knots and the swells kicked up to 3 to 4 feet. I dropped the jib and had fun going screamingly fast. The downwind floats submarined a few times, but I never felt like I was about to capsize. I only wish I had a housing for my camera so I could get some good action photos!
Niiiiiice setup! It's inspiring to see what the finished product is, especially attached to such a beautiful kayak. I also enjoyed your build gallery on your website. sailrig is nearly complete and includes strip-topped amas, as well. Unfortunately, my boat (CH triple) is not so nearly done....making for some l;ong tnights in the garage as it gets warmer here, finally, in Vermont.
Thnaks again for sharing your project!
Thats really an inspiration. What kind of speed are yu averging however with paddle alone?
Pete