tabernacle worries

Started by steve jones, 20 Sep 2011, 20:45

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steve jones

Im at the BR17 building stage when I need to think ahead of any modifications I need to make.
A concern I have, with a deck mounted mast, is relying on the luff wire,club boom arrangement. My solution is to utilise the spinnaker facility  and replace with a retractable bowsprit. the idea is to carry a fore stay outside the jib luff to a fiddle block sharing the mast head fitting with the jib haliyard.
Another modification I would need to make concerns reefing when single handed. I will make provision within the carbon fibre yard to fix a track enabling fixing screws, a simple wooden pole of about 35-40mm, and in my case of two reefs, 1500mm long not adding much to the top weight( certainly less than my S17 yard).
Other minor modifications are being considered- it's too late when you can't get at the ========= thing . 

Any other builders considering alterations ?

Julian Swindell

Hi Steve,
I don't have a gunter rig so I may be out of touch on this, but I don't really see what you are trying to do with the reefing track on the yard. Will you have an additional halyard going up the yard that lets you slide the sail up and down the yard? Or are you going to have to drop the yard to reposition the head of the sail and then raise it again? If the former, it sounds horribly complicated. If the latter, wouldn't it be easier to just lower the yard, clip the main halyard back on at a higher position and re-raise it all?

Regarding the fore stay arrangement, again, I have a conventional jib so don't have direct experience, but would query the idea of fixing what is essentially a safety stay. If the stay is taut, your self-tacking jib might not set very well. If it is loose, it might catch the jib as it tacks. I think failure of the fixing of a self tacker is very rare. I have not heard of it happening apart from collision damage, which can break any arrangement. If what you want is a backup, second support, couldn't you just double up the loop on the jib boom, so if one fails, the other catches it? I think it is far more common for a mast to fall over from a shroud shackle working loose than the fore stay failing.

Or you could just go for a Bermudan main sail and conventional jib and you don't have any of these problems...
Julian Swindell
BayCruiser 20 Daisy Grace
http://jegsboat.wordpress.com/
Guillemot building blog
https://jegsguillemot.wordpress.com/

Anthony Huggett

Hi Steve,
       Alas my build is way behind yours, and I'm not planning to deviate from the plans. I'm trying to clear the decks to start on the floor in October.

    I think I agree with Julian - the tension has to be in the jib luff to get it to work properly (that's the whole point of the club boom projecting forward to make a forestay tensioner). If I were really worried about a club boom failure, a line led from the eye of the forestay to the trailer strop eye would keep the mast up (albeit having moved a bit) if the club boom or any part of the stemhead were to fail.
    Someone commented elsewhere that they did this (for another reason) with bungee, to keep the club boom from scratching the deck when the jib is furled.

Anthony

steve jones

Quote from: Julian Swindell on 21 Sep 2011, 09:28
Hi Steve,
I don't have a gunter rig so I may be out of touch on this, but I don't really see what you are trying to do with the reefing track on the yard. Will you have an additional halyard going up the yard that lets you slide the sail up and down the yard? Or are you going to have to drop the yard to reposition the head of the sail and then raise it again? If the former, it sounds horribly complicated. If the latter, wouldn't it be easier to just lower the yard, clip the main halyard back on at a higher position and re-raise it all?

Regarding the fore stay arrangement, again, I have a conventional jib so don't have direct experience, but would query the idea of fixing what is essentially a safety stay. If the stay is taut, your self-tacking jib might not set very well. If it is loose, it might catch the jib as it tacks. I think failure of the fixing of a self tacker is very rare. I have not heard of it happening apart from collision damage, which can break any arrangement. If what you want is a backup, second support, couldn't you just double up the loop on the jib boom, so if one fails, the other catches it? I think it is far more common for a mast to fall over from a shroud shackle working loose than the fore stay failing.

Or you could just go for a Bermudan main sail and conventional jib and you don't have any of these problems...

  Hello Julian/ Anthony,
  I tension the luff of the jib with a lorry drivers knot, low tech' but effective , I do this on all my boats even when using kevlar.
Gunter rigs come in a number of haliyard arrangements, the Swallow boat system consists of a single haliyard which should you wish to reef requires lowering the yard and re-attatching to the reef setting( on my S17 it ment pokeing it through a hole) all very well if you are starring in a biblical epic with a crew of thousands, but I usually sail single handed. The idea is to drop the main completely and sail jib, mizzen.  I have found that a reefed main is preferable.
Gunter reefing that I have on another boat that works very well consists of a throat and peak haliyard, with the peak attatched to a runner in  track on the yard and is simple to adjust when single handed, just one extra cleat/rope. Another low tech' idea I used was the addition of a seperate reefing line that is attached to the reefing point on the yard and can  be instantly deployed. These mods' require considerations at the construction stage which was the point of my post.
It is fine to rely on the luff of the jib, if the wire was a more substantial, a link could be used across the club boom, but I think a tensioned fore stay ( I don't accept the interfence problem, given the correct geometry) would allow a safer option and possibility for a separate sail. 
I'm  not much further than you, Anthony, it's just best to think of these things while one can get at them.

All the best