Mast rake and shroud length

[Colin Morley]

I am setting up my BR20 after everything had been taken off it for servicing. I am struggling a bit with the length of the shrouds, adjusted by the rope strop to the chainplate. I was told that the bottom of the mast should be flat on the deck at the front. However, with the oval hole for the bolt in the tabernacle it is possible for the back foot of the mast to lift a little.
When I think I have it about right, when the length of the strop is about 14 cm, I have put a set square against the bottom on the mast and the "flat" foredeck in front of the mast and then the mast seems to be leaning forward. This does not seem right to me. Of course I can shorten the strop to angle the mast back but I would be good to know what is the optimal mast rake when the jib is under tension.
This seems an important aspect of setting the boat up for optimal sailing but as far as I can see it is not in the owners manual or the forum.
When racing dinghies the shroud length, mast rake and shroud tension was well defined.
Any advice please.

[Roge]

I believe that too much mast rake will drop the aft end of the jib boom and it will not clear the deck when the jib tension is right.

[Graham W]

Colin,

For some reason my chainplates are fixed to the hull at slightly different heights, so I try to tighten the strops so that the height of the bottom of the shroud eyes is the same (measured from the deck) on both sides - in my case, 7.5".  This means that one strop ends up slightly longer than the other.

I then tighten the jib halyard so that the front of the mast and the front of the tabernacle are more or less in line.  It might be a bit rough & ready but seems to work. I don't use the self-tacking jib any more, flying my conventionally-sheeted jib off a short bowsprit. This might make a bit of difference to the geometry of things.

[garethrow]

Colin

Not sure if this helps, as I have a Storm 17 (not all boats are Bayraiders!) but I have the same challenge when renewing the strops at the bottom of the stays - a job I have just done for my first sail of the season.

There are 2 or 3 guiding principles I use (gleaned from Matt years ago!):

1. Ideally the rake of the main needs to be close or equal to the rake of the mizzen - so stepping back from the boat to eye up comparative angles is a good start. If they look like a 'Y' or an 'A' - you have problems. Assuming mizzen rake is fixed - I have to vary the main.

2. Take care to get the mast upright from side to side - don't assume your stays are identical length (fixing point variation) - have a good look from the stern and adjust accordingly.

3. If you have the masts lined up nicely but the jib boom is hitting the sampson post - then you can either compromise your mast rake and inch it forward a little until the jib boom clears or (if you have room at the head of the sail) lengthen the strop or shackle that attaches the jib boom at the front end in order to raise the sail a little higher.

I am not sure how critical all this is, but as an ex dinghy sailor of far too many years - it is difficult to get out of habits! The joy of a Storm though is that it is not a highly stressed rig; it is simple and held together with bits of string. I therefore don't get too stressed about detail.

Regards

Gareth Rowlands
Gwennol Teifi

[Simon Holden]

Colin

I too had this problem when setting up the mast on my Storm 17 as it is fairly important to have the rake reasonably accurate.
I contacted Matt who kindly sent me PDFs of the plans for the S17 - attached hopefully for ref (I'm sure he could do the same for the BR20).
I then opened the 'profile' plan and scaled up the image before printing it out on A4.
I measured the angle between the front face of the mast and the kingplank on the plans and made up a plywood angle guide accordingly.
I then used this guide (a bit like a set-square, although < 90 degrees) on my boat between king plank and mast, and set the lengths of the shrouds accordingly whilst playing with the set of the jib to get all the tensions correct.
Frequent reference back to my 'set-square' ensured everything stayed true.
Hope this helps - it worked well for me!
Simon