Rudder downhaul jamming

[dermot]

Last year I replaced my rudder strings as per the instructions in the library (https://www.swallowyachtsassociation.org/?page_id=1246). I also followed the suggestion to use 4mm dyneema instead of 6mm which seems to fit the cleats better and allows more room between the black roller and the rudder head. It does seem to have made lifting easier.

However, using it on the water for the first time last weekend, on two occasions the downhaul rope jammed between the rudder and the steel housing with the rudder at the halfway point, requiring an undignified lean over transom to sort out. Fortunately the rope was accessible just under the steel housing and could be pulled free, but it could also have got jammed inside the housing and been much less accessible. I've tried to attach some photos which show the problem below.

I've found various posts on this forum around the topic and can see I have a few options to address this but this seems a subtly different problem to those described by others to date. As I see it my options are one or all of:
- go back to using 6mm rope which should be less inclined to work its way into the gap
- install something like a PTFE washer to make less space in the gap (and reduce friction)
- replace the black roller at the rear end of the square steel tube the ropes pass through with some sheaves like those at the front end. Not sure if there is room however for the same model (to allow space between the sheave and the rudder)

So I just wanted to check in with the forum to see if this has been experienced elsewhere and if there are any recommendations on the best way to fix this. Any advice gratefully received.

Thanks
Dermot

[Graham W]

Dermot,

The PTFE washers ease friction but as you have quite big gaps between both sides of the rudder and the stock, I think they would also close those gaps.  You might find that the rudder then rattles around less.

It's a bit irritating having gone to the trouble of drilling out the rudder head to install 4mm line, to then have to go back to 6mm.  However, I think that this would also help with your problem.  And it's easier on the hands.  It's also possible to use a combination of blocks on the tiller to get a bit of mechanical advantage on both strings.

I don't know about the feasibility of replacing the aft black block with sheaves.  The front sheaves I think were a replacement for a similar black block originally used on early BR20's and must have been an improvement.

[dermot]

Thanks for the advice Graham.

I've realised I have another issue in that the gap between the rudder and stock is wider at the forward side (enough for a 4mm rope to jam in) but very small at the other side so it might be difficult to squeeze a PTFE washer in there. But I'll investigate the options further, the most obvious seems to be going back to 6mm rope with which the problem didn't materialise.

[Graham W]

You can see the irregular gap in the first of your photos.  I wonder if the gap will become more parallel if you loosen the bolt that the rudder pivots on?  If it does, then taking the bolt out and inserting 2mm thick discs of PTFE either side should sort things out.

[Matthew P]

CDs make good gap-filling washers, as discussed in this 2014 post:     

https://www.swallowyachtsassociation.org/smf/index.php/topic,1001.0.html

Some argue that Barry Manilow CDs are smoother than say, Meat Loaf, but I have no objective evidence.

A perfectly flat interface between rudder and fabricated steel bracket is probably almost impossible to manufacture so the gap between the stainless steel plates may not only be wider than the rudder but also irregular.  This is not necessarily a bad thing provided there are three points of contact widely spaced around the pivot bolt to steady the rudder when it is down and doing its business.   

Matthew
ex-BR20 Gladys   

[dermot]

I don't believe there are any Barry Manilow CDs in the house, but I may be able to dig out some Bee Gees.

That said, I did try to fit (blank) CD washers when I changed the rudder ropes, but there wasn't space - I think the rudder housing is that shape even without the bolt. Also I think whatever goes in there also needs to extend to at least the outer edge of the rudder head, to stop the rudder rope getting into the gap.

Interesting point about the 3 points of contact - perhaps what I need is something like an arc/strip of PTFE stuck to the inside face of the rudder housing where the gap is widest. Although not sure what glue I would use and it may just make a mess of the face. I'll try perhaps with a 1mm PTFE washer to start with.

[Guy Rossey]

Posted by: dermot « on: 13 Jul 2021, 22:31 »
"... I also followed the suggestion to use 4mm dyneema instead of 6mm which seems to fit the cleats better and allows more room between the black roller and the rudder head...."

In order to achieve this - and also to reduce the effort of lifting the rudder - I connected a hoist with a thinner rope to the lines both sides of the helm (see pictures).
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Catchando Bay , BR#48