A Photo & Discussion Forum for Wharram Design Enthusiasts
The Tiki rudders are supposed to be hinged with 4 millimeter polyester string. Have you been able to tie the string in the figure-of-eight fashion so tight, that the rudders do not move up and down. If not, how big up-and-down -movement is permissible? I think that it is unavoidable, that the rudder touches the stern post right in the center line of the stern post, chafing the paint. I guess the stretch of the string will not be an issue, since the string is glued to each hole both in the rudder and the stern post, but the question is: how to get it tight enough before applying the epoxy.
I had difficulties with the tiki 30 rudder. I think by its weight it should have a guide pin under the rudder attached to the skeg, as in tiki 38. But minor Wharrams should not have this problem. Alas, my cables are not glued. I change each year.
we wrap the hinge line around an axe handle for leverage on each turn. Once e have a turn tight we drive a wooden wedge into the hole to hold the tension while we rig the next turn. once all turns are in we glue the rope to the holes in the rudder and the sternpost with super glue. We do not reuse rudder lashing lines as extra length is needed to install and we drill out the line to unglue it.
We insert 7 mm dia aluminium tubes in the lashing holes in the rudders and sternposts. First you drill the holes large enough to accept the tubes , coat the inside of the holes with epoxy and when dried fix the tubes in place with sikaflex or similar . Purpose of this is that one can easily remove and replace the rudder when desired ,for example to repair damage . We use 6mm lashing rope . There is a little bit of up & down movement but we have never found that to be a problem . If it does worry you then Boat smiths' lashing method will work well.
Siam Sailing, Phuket
I fitted my rudders exactly as stated in the plans, except for using dyneema.
My plans show a clearance gap between the rudder stock and the sternpost, are they still like this?
Clearly, if you maintain this clearance, then no matter how tight you tension the lashings, there is going to be slack when the clearance packers are removed after the lashings are complete. But, if you don't have clearance, how can the rudders freely move without friction?
I am at a loss as to why no one seems to have addressed this obvious potential problem in these plain terms.
I tightened my lashings using an Estwing claw hammer pivoting/levering over a purpose-made rubber pad, with the dyneema cord wound around the hide handle of the hammer. I wouldn't use an axe, they are for chopping. A hammer head/shaft is an ideal lever.
So - in spite of the tightest possible tension on the lashings, wedged and clamped each time, there is at least 6mm vertical sag on the rudders against the stempost giving a potential cause of rubbing and ingress later of water into the rudder and /or stempost. Fortunately I allowed for this sag in offsetting the epoxied drillings for the cord. However, potentially the rudder can rub against the stempost; flotation of the rudder is ?/weight of tillers and tiller bar. Less I think.
Once again: I have lost time working out a simple retro solution to this problem, which I may comment on later - if it works.
Rebuilding a year or two after launch is not in my scenario, building takes too long. Wharrams need to address this, there are too many areas of design like this. I take plans literally and follow them to the letter, unless actual proved experience shows them to be wrong.
I would use conventional fittings in a rerun. Much, much. faster to fit and no sagging.