A Photo & Discussion Forum for Wharram Design Enthusiasts
I guess the TIki 30 rudders are similar to the Tiki 31- correct me if I am wrong.
I got hold of Bill Belcher's book last winter and also have Djikistra's (spelling from memory) and if this winter proves to be another lockdown scenario will have a go at making the self- steering rig based on the QE model + trimtabs which Hanneke Boon appears to have based her design on. There are a few videos around of it working at sea successfully.
I enquired @ Wharrams for the price of their plan for the self- steering rig Hanneke has drawn up. Various successful sailors say it works - but I baulk at the silly price of the plan which is quite derivative as far as I can see of Belcher et al. You could say with justification that I am a bit (censored) - minded but if I wasn't I would never have built my own boat.
My rudders are sheathed and finely profiled with some effort when I made them so I don't want to butcher them but will do eventually I suppose as my ambition has been for many years to do a solo trans-at in a boat that I have built from scratch. For me it's two -fingers to corporatism and the materialist wasteful and destructive consumer culture and one up for us makers who have worn out our joints for our craft.
I'm not interested in electronics so there isn't much chance of me installing that for self steering.
If you look up the website for Tiki 38 Luckyfish you will see Hanneke's design of windvane self steering operating and explained there (in 10 great things about Wharrams etc). One vane for each rudder. You can see the trim tabs operating under sail. The aft edge of the Tiki 38 rudders look straight to me but I am happy to be corrected if wrong. The Tiki 30, 31, 38 profiles seem more or less similar to me, but I only have experience of the 31. There's always the option of paying £60 for the plan of course!
Sorry no links, I am in a hurry to catch the tide.
I looked at my rudders on the boat today and the aft edge is straight until the waterline then there is a rounded corner going to the horizontal bottom edge. So when I mount my trimtabs I will add on a fillet piece which will extend the aft straight edge of the rudders to the horizontal edge at the bottom, so that the trim tabs can go more or less the full length under the water to match.
If you have a hollow curve aft edge to your rudders maybe you can add a fillet piece to those edges so that they are straight and can match up with a straight trimtab.
The Luckyfish video is a really good and clear demo of the gear working. When I was reading up on this I also looked at the sailing videos I could find of Tiki 21 Cooking Fat (a single vane rig was transferred from one side to another as required if I remember rightly).
Belcher's details show mostly balanced rudders, with everything vertical.
Same problem here, rudders are "hollow" and I'm not willing to pay Wharram's prices.
In Sheet #1 of the plans (structural details) and in the drawings on the Building Plan Book you can see that the rudders are NOT hollow, but then in the Dimension and Ply Cutting sheets the rudders are hollow. There might be a mistake in Sheet #1 or maybe the rudders were hollowed for some reason, so I wouldn't mess with them. What I'm planning to do (might change) is that the trim tabs will go up to the highest part of the hollow, which I think is above the waterline and there will have a couple of ears (one each side) which will have rope going through a flat cheek block on the side of the rudder (remember, it's above the waterline) and then up each side of the rudder up to another cheek block (on each side) and from there to wherever is needed. This is not a definite plan, will wait to have the boat ready to see if it will work.
Another way might be to make the trim tabs go up to the highest part of the hollow and fix a stainless steel cheek to the top of each side of the tab in an angle running parallel to the back of the rudder up to the desired height (from the top of the hollow to the top of the rudder is only 350 mm, not much), maybe with some ply between the cheeks to reinforce them, the cheeks not fixed to the rudder but only to the trim tab, the rest you do as if it were a straight rudder. This way might be simpler and less room for problems.
I agree with the plan cost. I've also been trying to figure out how to realistically mount two units on the T26. May not be possible.
There is another plan available from the Sailing Wave Rover YouTube channel that has many thousands of ocean miles behind it. It's available as diy plans for about 20 pounds I think. There are lots of videos on his channel of it working and how to buy.
Hope it helps.
I'm sorry for the extra post but I couldn't find this link earlier.
There is another diy option with an open source design ie free that was referred to elsewhere on the forum.
Hope it helps. I'm certainly going to look at it more closely.
I think this mock-up will be the simplest way. I will cut a bit off the lower trailing edge and add a bit of faring is above the waterline. That should give me the proper angle for the pivot rod