Monday, July 04, 2011

Building ‘Sharpy’ Part 134

Bow shoe

Stern shoe

I’m going to leave you with a few photos without adding too much text. This is an exciting time because I’m testing the rig and keel. I was surprised how easy it was to insert the keel and add the second weight. Perhaps this was due in part to spraying the keel with silicone wax.

Inserting keel

I shall have to make adjustments to the lining up of the keel weights. How they came to be out of line, I cannot imagine. I feel sure they were in line when I was making the keel. A friend has suggested how I can get the weights to line up. That could be number one priority for tomorrow - if I can find time for boat building.

Full sail


As far as I can tell, I’ve finished the boat, with the exception of sorting out a better reefing system and lining up the keel weights. I’ll probably opt for a leach downhaul plus independent sail ties through cringles along the reefing line.


Brian said...

Great to see you "aboard" Bill! When she is reefed, do you lower the centre of effort some how? Perhaps "release downhaul and increase kicker", in Scow terms, to bring the boom more horizontal?
Please take some videos for us followers when you launch. Had a wonderful 1 hour skype chat with John Welsford this morning. Brian

William Serjeant said...


That is true; I can lower the centre of effort as you suggest, but for going to windward, having a more vertical luff is likely to be more efficient. I'll have to see what works in practice. Even when running, a more upright sail is likely to be better, because it brings the centre of effort closer to the centre of the boat.

I'll have to try these things to discover what is best - that's part of the fun with a new boat.


Brian said...

I think the centre of effort so high up in reefed conditions would scare me a bit Bill. I was thinking by releasing the downhaul and pulling on the kicker the rig would move lower and forward, bringing the COE more inboard as well. Just don't do what I always do, going out in too much wind in a new boat.
had a wonderful sail in my Oughtred Tirrik on Sunday Bill. Links to video clips here - you will soon be out enjoying such lovely conditions -

William Serjeant said...


I think I could do what you suggest, but to bring the rig forward I would have to ease the rope that keeps the boom close to the mast - because it holds the tack in position, the yard can be peeked up by hauling on the halyard. I've forgotten the name of that particular rope that goes through a hole in the boom at the tack end and passes around the mast, with the upper end over the boom and the lower one under it, then the two ends are tied together.

In fact, this is my first experience of a lateen sail, this one having a boom, unlike some of the Mediterranean ones.

However, for efficient windward sailing, one needs a good vertical luff. One answer would be to have another halyard running through a lower block. Unfortunately the halyard and block would increase windage and weight aloft.

The reefed sail is not unlike some Polynesian sails, from which the wind can be spilled quickly by releasing the sheet.

Don't forget that 'Sharpy' is a keelboat. I should not have to sit her out. The prototype boat sails to windward in a Force 3 with full sail at around 30 degrees from vertical.

I can see there will be a learning curve, but I do know that from a 90 degree knockdown, the boat rights herself! That's what I've been told. I hope that doesn't happen to me...... There are times when you have to trust the designer.

You build a boat according to the plan, and you hope it will meet your expectations. I know this did not happen with your Raid41.

I'm hoping that I shall not be disappointed with 'Sharpy'.


Brian said...

I fear I have offended you Bill, my deepest apology if I have. Any reference to RAId41 causes me the greatest discomfort - it was such an unhappy project in every way.
I am absolutely sure sharpy will be a tremendous success.
I was re-reading my book by W P Stephens "Canoe and Boat Building" and came across this drawing of how the reefing of a lateen sail is achieved. The drawing does show the boom moving forward to bring the boom back down to the original angle after the reef is tucked in. The drawing shows a half jaw on one side of the boom to hold the boom to the mast in the forward position.

the book is on-line here and go to "sails and rigging"


William Serjeant said...
This comment has been removed by the author.
William Serjeant said...

Thank you Brian,

I was not in the least offended. I'm sorry to have reminded you of the unhappy episode with your Raid41.

The original 'Sharpy' has undergone extensive testing on small lakes, which has ironed out any wrinkles for that sort of sailing. I'll be subjecting my boat to more rigorous conditions associated with the tidal estuaries of the River Crouch and the River Thames.

If my sea trials go well, I'll be down to your patch and bring that lead I promised at the same time.