Thread: Another UK GIS (Gizzle in Hants)

Originally Posted by Boatmik

Exciting and interesting and milking the internet for all it's worth!

MIK

Milking the Goat for all she's worth

Exactly Simon,

One of the areas where these alternative boats and non mainstream rigs have missed out is on this white heat of careful improvement and study.

That's basically what drives my design work ... to produce boats that are as state of the art as possible - lightweight, good foils, efficient rigs, balanced helm - all from my racing experience and the years of development of Australian plywood racing craft (not that it wasn't happening elsewhere ... but that's all I had available in my neighbourhood).

The plans encapsulate a lot of that stuff .. though I think a lot of people don't realise it until they get the boat on the water and find that there is something special about the performance you can pull out of the boats.

But the problem ... is that without help and interaction from others ... my knowledge is stagnant and the boats are frozen in time.

But I am so happy that we have attracted people with either a good sailing background and a technical bent (or both) so that they want to try different things and are strong enough to declare both the successes and failures.

So when some improvements are found - much stiffer booms, somewhat stiffer yards, the bleater and vanghaul, beefing up the downhaul even further, the square hollow and birdsmouth mast options, the potential of really light timbers like paulownia, the smaller first reef, maybe more boxing in of the mid seat, more considered reefing (though I think this is less developed than some of the other areas at this point), setting up boats for expeditioning, a clearer idea of traveller setups (both initial and sailing), tweaking more windward performance out of the boats.

Not to mention greater exposure for the potentials of this kind of setup ...

... all of that is down to the goat builders and sailors.

I had four hours in Sneaky on Saturday and had a really nice sail although at times I could have done with a bit more wind. It was generally sitting at around 5-6kts occasionally a bit more (enough to allow me to sit on the hull side) but generally I was sitting in.

Having tried the Red bleater (tied to the boom only with rope around the mast) and now the Blue Bleater (loop from mast to boom-end) I think I prefer the second option, it’s simpler and works. The only improvement I can think would be to have it permanently rigged to the mast at the correct height then it would just be necessary to connect the forward end to the boom (with a loop as discussed earlier).

The downhaul/vanghaul is attached to the boom approx. 6” aft of the mast this seems to work well. I have the lower part of the vanghaul attached to the deck to the port side of the mast, this was fine when it was just a downhaul but as a vanghaul It would be better to have it attached just aft of the mast. When sailing downwind in really light airs the tension on the vanghaul was preventing the boom from freely swinging out on the starboard side, centralising the vanghaul behind the mast should fix this.

I have also removed the block from the yard and have a loop instead, this caused no problems at all although I guess it may wear the loop eventually so will probably reinstate (as I already have the block).

Originally Posted by Gizzle

I have also removed the block from the yard and have a loop instead, this caused no problems at all although I guess it may wear the loop eventually so will probably reinstate (as I already have the block).

I lashed a 1" diameter stainless steel ring in place of the block and it has been working very well. Stainless Steel Rings

Hi Simon,

I know you had your boat sailing nicely before. Have you given the vanghaul and bleeter a try to see how they compare?

MIK

Hi MIK,

I have sailed once with the bleeter but did not move the downhaul back to act as a vanghaul. To try the vanghaul I will need to prevent it's attachment point from sliding forward on the boom. I need to experiment more with this but I'm pretty happy with how the sail sets as is. My new very stiff boom combined with 6:1 downhaul seem to be able to control twist reasonably well.
The biggest advantage of the bleeter, so far, has been the elimination of the boom scooting forward while hoisting sail.

Sailing season is getting ready to start around here so I'll have lots of opportunities to play with this in the coming months.

Originally Posted by SimonLew

Hi MIK,

I have sailed once with the bleeter but did not move the downhaul back to act as a vanghaul. To try the vanghaul I will need to prevent it's attachment point from sliding forward on the boom.

The really lo-tech way that I used was screw in the top of the boom. I haven't given the vanghaul a proper go yet. Our early season winds are all over the place. Come on the North-Easters!

A little bit of a controlled sail twist is to benefit while reaching because the higher up, the faster wind. The apparent wind direction will be a little bit different higher up than at the foot. (Not that I know how much sail twist you actually get with a GIS and the balanced lug)

Originally Posted by woodeneye

The really lo-tech way that I used was screw in the top of the boom. I haven't given the vanghaul a proper go yet. Our early season winds are all over the place. Come on the North-Easters!

I would add a wrinkle from the racing guys with bigger boats in terms of providing these sort of attachments.

They will use spectra rope - 4mm and have the screw around 400mm further back along the boom than really needed.

Then the rope is taken to the actual point with equal length tails and each tail is wound spirally round the boom towards the back of the boom but in opposite directions - one clockwise and one anticlockwise. The ends are then hooked over the screw or put through a relatively light deadeye or hole in the boom.

This removes most of any shockloads from being directly applied to the screw or fitting on the boom and also means the hole is away from the point of maximum stress (not that it matters because when timber is loaded in compression (eg top of boom) if you drill a hole and put a screw in it there is no loss of strength. That's from my favourite engineering book "The Science of New Materials or why you don't fall through the floor" - J E Gordon.

It just occurred to me that you can have one screw position like this and then adjust the actual final location of the vanghaul by altering the length of rope and the number of spirals.

The angle of spirals should be parallel to the angle of the vanghaul.

MIK

Originally Posted by engblom

A little bit of a controlled sail twist is to benefit while reaching because the higher up, the faster wind. The apparent wind direction will be a little bit different higher up than at the foot. (Not that I know how much sail twist you actually get with a GIS and the balanced lug)

Yes ... an important reminder - and a good reason to have leach ribbons or sail tufts.

On bigger boats there can be a significant difference tack to tack because of wind shear - the wind actually changing direction up higher. I've experienced a 15 degree difference from tack to tack on a bigger boat in a race.

Not likely to be a factor with shorter rigs like the goat.

MIK

Originally Posted by engblom

A little bit of a controlled sail twist is to benefit while reaching because the higher up, the faster wind. The apparent wind direction will be a little bit different higher up than at the foot. (Not that I know how much sail twist you actually get with a GIS and the balanced lug)

Yes, also need lots of twist to depower on a reach in high winds when you cannot hold the boat flat any more. At the Brisbane Master's Worlds we had some amazing sustained reaches in big waves. In 20kts and above it was much faster to let the vang go almost completely and have the bottom third of the sail working really well rather than sheeting out to depower. This method helps steering in big waves as you have to keep the boat flat at all costs. Dipping the boom is not fast. It seems strange, but most of us had maximum Outhaul and Cunningham on the reaches once conditions became too fresh.

Thinking back to that famous pic of Nathan Outteridge wearing the snorkel, we could have done with that equipment on the reaches as it became quite difficult to breathe through the constant spray!

Attachment 222629

At 0.55 you van see what happens to the boat that doesn't have the vang loose enough at the top mark!
[ame="http://www.youtube.com/watch?v=-AWdsHsjxq8&feature=player_detailpage"]Laser Worlds 2010 - Bruno Fontes - YouTube[/ame]

So basically, Bruce, in extremely heaving winds, releasing the vang allows the top 2 thirds to twist off and you use the bottom third for power?

That's reaching. If you try it broad reaching or running the top will never depower when it twists off just give you forces that will make the boat roll to windward.

You need to be on enough of a reach so the top of the sail flaps visibly but the bottom of the sail is still full.

MIK