BR20 Stemhead - Screw pulling from stem.

[Rock Doctor]

Greetings from Oz.
Spring has sprung and the first serious sail is on this weekend with the Swan River Retro Race Series (gaffers and classic yachts of all ages and sizes - see http://www.gaffrigsailinginwa.org/retro-yacht-series-galleries/ ) out of Royal Perth Yacht Club.

Consequently Gryphon has undergone a pre-season once-over during which I was reminded that the stemhead has been moving and pulling out the top screw. See my photo attached.

I have previously filled this with Epifill and re-drilled it and replaced the original screw. After it pulled again I Epifilled it and inserted a larger screw and still it has pulled. I note that there is not much "meat" in the GRP in this area and given the location it is difficult to build up the backing in any meaning full way.

The cause - I think this fitting is loaded with a forward force when running and/or broad reaching. On a few occasions when broad reaching the headsail oscillates for short periods, this may be working the steamhead.

I wonder if any of the BR20 clan, or others with similar fittings, have any experience of this and who may be able to offer suggestions.

In the meantime I hope the autumn sailing is being kind to those in the northern hemisphere.

[Peter Cockerton]

Rock Doctor

From looking at my boat i reckon the problem is down to the crank in the stainless being to low. The bend on mine does not start until the stainless band is some 15 mm above the bow. As a result the upward force exerted by the jib is tending to pull the stemhead up and forward and as a result pulling out the top fixing screw. With the crank in the band higher the upward force from the luff wire would tend to pull the band into the bow and not stress the top fixing.

Peter Cockerton

[Rock Doctor]

Hello Peter,
thanks for your observations although. I wonder why there are difference in the steel stemheads. I see we both have GRP versions and I wonder why the difference in the position of the crank.

Maybe later versions have this problem - or - the fitting of the stainless strip varies from boat to boat.

Will wait to see if there are any other replies.

Regards from the antipodes.
Chris Robinson

[david]

Hi Chris,
               I am experiencing exactly the same thing with my BayRaider 20. I think we are close in number also. (Mine is #80). I have shortened the shrouds and given my lashings more room for adjustment. I was thinking it was due to my mast rake being incorrect. (See the posts on mast rake). I was able to adjust the  mast angle to be more in line with what was stated as appropriate. My mast angle was forward, prior to this adjustment. Have you looked at this? I will post a picture of the stemhead after my sail this weekend. It is a little hard to see in this picture.

[Michael Rogers]

Chris, I don't have a BR (though I did have a Storm Petrel with a club boom), so I'm really speaking out of turn. However, looking at your pic I wonder whether the strop from the club boom is twisting the steel stemhead band, thereby eventually loosening the screw, rather than pulling at it? I could imagine that on some points of sailing the twisting force could be considerable.

Something other than a twist shackle, to reduce or eliminate the element of twist, would at least show whether this had something to do with it. Just a thought!

Michael

[Rock Doctor]

David and Michael,
thank you both for your observations and comments. David, my mast definitely has an aft rake but will check again this weekend to see if it is the 4-5 degree that Matt suggests.

Michael, Your comment too is interesting, I have a swivel shackle I can try here although the twist shackle came with the boat as the fitting for this position.

Regards to all
Chris