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Post by so40gtb on Jun 16, 2012 0:19:37 GMT
On the SO40 that we recently acquired, the boom end doesn't clear the bimini when tacking with the vang pulling the mainsail down to flatten it in significant winds. The "tacking dance" therefore includes he added steps of releasing the vang, pulling up the topping lift, and ensuring that enough mainsheet is out so that the boom end clears the bimini's front bow when coming about, reversing the process once on the opposite tack.
The "obvious" solution is to have the canvas shop shorten the bimini by 5-8 cm or so, to ensure clearance regardless of boom elevation.
Has anyone else been down this road (applies to any size boat)? Is there any compelling reason not to shorten the bimini?
--Karl
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Post by MartyB on Jun 16, 2012 3:41:58 GMT
You might also look at removing a triangular part of the main sail foot! Might very well be cheaper and easier than lowering the bimini. Not sure how well the boat will sail after, but it would fix the issue. Or possibly better yet, buy a new mainsail! which in the end is probably the MOST expensive fix!
marty
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Post by touchngo on Jun 16, 2012 9:51:26 GMT
We had the same issue with our SO40, even after replacing the Main, Boom and Bimini!. What we found was that if we put enough tension on the forward strops that the Bimini could be tensioned enough that we have a few inches clearance. See the picture here prior to tensioning the forward strops;  i1233.photobucket.com/albums/ff394/Paul_Truscott/boomtouchingbimini.jpgThis summer we will be lowering the hinge point for the middle bimini support arch and the slack will be taken up by more tension on the forward strops. No need for recutting the canvas, jiggling with the main etc... If you're worried about the old holes that the hinge is riveted to, you can always have put a rivet in them, but in all likelyhood they're not going to be the cause of the stainless failing (unless you want to put tons of load on your Bimini with solar panels and the like). See pic here;  i1233.photobucket.com/albums/ff394/Paul_Truscott/biminisupports.jpgWill post pics after we've made the changes (not on the boat till next month). Cheers, PT. |
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Post by so40gtb on Jun 16, 2012 11:40:26 GMT
PT,
Thank you for the comprehensive discussion and pix. Our bimini covers only the aft third of the cockpit, over the wheels. It is its forward bow that conflicts with the boom and, not its aft bow.
That said, we've looked at realignment of the bows as a possible solution, but it appears that the feasible adjustments either invite head-knocking on the forward bow or would necessitate a recut of the backstay slots.
Marty,
My sail guy suggested adding new clews above and forward of the existing ones. Since the main is loose-footed, that's feasible, but it sure seems kludgy.
--Karl
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Post by touchngo on Jun 16, 2012 17:29:11 GMT
Hmmm... that eternal trade off..... headroom or performance? We have the advantage on you, in that being vertically challenged, we can find an optimum balance.
Not sure what to suggest.
Canvas work is cheaper than re-cutting a mainsail IMHO. Moving a fitting can be far cheaper though.
If you were to shift the mounting point for your gooseneck (boom to mast connection) up, do you have a little clearance left on the main at max hoist that would mean that you don't have to re-cut the sail at all? (it is a serious question as it is not uncommon for sails to have another 4-6 inches of max hoist left).
As I see it , with all the factors involved, one has to change. Either you get shorter and your bimini gets lower, or your boom gets higher.
Cheers, PT.
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Post by MartyB on Jun 16, 2012 18:39:08 GMT
Karl,
T-go hit the nail on the head. "WHICH" option is best will depend on a lot of things. i could see raising the boom, cutting/getting a new main that is slightly smaller that will not allow it to hit the bimini. Lowering the bimini.......or in my case, dump/toss the blinking thing! Then all is good!
At the end of the day, which is right or wrong.......you have to decide on that one.
Marty
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Post by Don Reaves on Jun 17, 2012 10:57:03 GMT
I had my bimini custom made for the boat when it was new. I had the canvasmaker build the bimini so it didn't come forward far enough to interfere with the boom, so the height of the bimini or the boom doesn't matter. My boat is an SO 35, so the geometries may be different from those on the SO40.
Don
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Post by hoppy on Jun 17, 2012 11:39:38 GMT
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Post by DUET on Jun 17, 2012 22:45:34 GMT
I have a 50 DS with exactly the same issue. I would have thought the canvas maker in Annapolis would have been aware of the problem. My boat has a classic main vs the in mast version. Almost all the new boats delievered seem to favor the in mast. To add to the problem, I had side panels made for cold and bad weather sailing. Now a lot of re-cutting.
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Post by so40gtb on Jun 25, 2012 2:34:48 GMT
I realigned the forward bow to lower the bimini height at its front, so that it barely clears my head. I also realigned one of the rear support arms. These changes, along with attention to the topping lift when tacking, seem to be providing sufficient clearance, so far.
The bimini doesn't look nearly as smooth - rather discontinuous at the bows - but looks are secondary to damage avoidance and sailing performance.
We haven't been out in winds above 20 kt since these changes were made, so it's unclear whether the main can be flattened well enough in such winds without causing boom-bimini conflict.
--Karl
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