Thread: GIS handling characteristics

Originally Posted by callsign222

OK, in my very un-scientific bending experiment I get the following results:

Approx. 25lbs bends my 35mm x 35mm spar:

2" (5mm) if suspended from the head to the peak of the sail

2.5" (63mm) if suspended from end of spar to end of spar.

Those numbers are almost exactly the same as other people have posted for their yard stiffness, so unless Mik thinks thinning down/tapering your yard more is a good idea, I guess you can cross that off the list of things to try.

I just checked the theoretical stiffness of 35x35 mm square section versus 40mm dia round, and the stiffness calculations come out almost exactly the same, so good to see theory agreeing so well with your very scientific bending experiment!

Cheers, Ian

Joost, look at this picture of my boom, maybe this is something you want to try?

I took a copy of my yard (35x35mm) and added a horizontal 35x17mm strip almost but not quite the full length. Stiffer than the yard, but with just a little give. Maybe a variation on this is something you're looking for.

I admit I have not been following the spar thread as closely as I should have, but it seems to be working well.

(Before people start squawking my downhaul has since been changed, this is a picture from the maiden voyage...)

Originally Posted by callsign222

Joost, look at this picture of my boom, maybe this is something you want to try?

I took a copy of my yard (35x35mm) and added a horizontal 35x17mm strip almost but not quite the full length. Stiffer than the yard, but with just a little give. Maybe a variation on this is something you're looking for.

I admit I have not been following the spar thread as closely as I should have, but it seems to be working well.

(Before people start squawking my downhaul has since been changed, this is a picture from the maiden voyage...)

Hello Callsign,

So if I understand correctly, your booms measures 35mm width * 52mm height? Very similar to the dimensions I have in my mind for a new boom. Will order the wood this evening.

Thanks & Regards,

Joost

Yes, exactly.

Except the last 10"/25cm or so, which are still 37x37mm.

A good day today. It was really blowing, however, I did not go solo, I went with a friend.

Full up sail, no reefing. Again, some difficulties getting the sail all the way up and appropriately tensioned since I have to raise sail while underway. The boat's insistence on falling off the wind to broadside makes sail raising hair raising.

The boat has always been great with another person on board, and today was no different. Wind was anywhere between 10-20 kts, definitely F5. At some points we were really moving at times. In some heavier portions she really shouldered her way through. A little spray over the bow and in the deck, but not much for the size of the waves. She settled in and got steady, it was nice. I shortened the area of the sail forward of the mast, and this helped with some pointing and tacking problems from before. I had to move the yard-block a little forward, but it would slip sometimes, I had to reset twice (yes I'm using the cowhitch). I still got some forward creep of the downhaul, I need one extra block and maybe Mik's clamp idea to help keep it situated.


A few things that I need to figure out:

1. The placements of the grommets for the foot tie-down and along the yard sometimes interfere with the downhaul and the haylard block on the mast.

2. Thinner spectra/dyneema whatever line for clew, tack, head, peak tiedowns would give me better tension since I could take a couple of wraps rather than once through-- see Bruce's rigging pictures.

3. Also, I need more tension along the foot. I can't get hand tight enough.

4. I had a funny wrinkle in my sail running from the head (forward end of the yard) diagonally down to about 2 feet/60cm behind the mast. What's causing this/How can I get rid of this?


Finally, I think a large part of my solo problems might be with the lake and the winds I'm sailing in. Today we had massive shifts in wind, at one point we were full downwind while flags on the shore were pointing in exactly the opposite direction. Sometimes, we had 180 deg. wind shifts in channels within 3 or 4 boat lengths... I kid you not. And this wasn't a zephyr either, it was a strong wind. Other times we would go from both on the rail to scrambling to keep from falling backwards into the water in less than a boat length, even though the water never betrayed a change in wind velocity. It was an athletic day for sure, I am sore.

I'm looking forward to getting her out on the ocean with a dependable breeze from one direction so I can get a baseline.

Maybe someone more qualified will chime in, but here are a couple comments:

Regarding #1: I think no harm will come from omitting the lacing tie from the occasional grommet to prevent conflicts with other rigging.

Regarding #4: It sounds like the downhaul may be bending the boom more than what the foot round in your sail can accommodate. The probable solution is to stiffen the boom, but as a quick experiment you might try loosening the boom lacing ties in the neighborhood of the wrinkle (to simulate adding more foot round to your sail) and see if that makes it set better.

Grant

Originally Posted by callsign222

I had to move the yard-block a little forward, but it would slip sometimes, I had to reset twice (yes I'm using the cowhitch). I still got some forward creep of the downhaul, I need one extra block and maybe Mik's clamp idea to help keep it situated.


A few things that I need to figure out:

1. The placements of the grommets for the foot tie-down and along the yard sometimes interfere with the downhaul and the haylard block on the mast.

2. Thinner spectra/dyneema whatever line for clew, tack, head, peak tiedowns would give me better tension since I could take a couple of wraps rather than once through-- see Bruce's rigging pictures.

3. Also, I need more tension along the foot. I can't get hand tight enough.

4. I had a funny wrinkle in my sail running from the head (forward end of the yard) diagonally down to about 2 feet/60cm behind the mast. What's causing this/How can I get rid of this?

Hello Callsign,

Try the following knot for attaching the downhaul and halyard block to the boom and yard:



It is called a prusik knot. Here is an instruction how to tie it on the boom and yard: The Prusik Knot or Triple Sliding Hitch

Rigged it should look like this:



If it still slides when rigged like this, you can make a third loop which will for sure stop any sliding.

1. One inch to the left or right doesn't matter much in my expierence.

2. I use 3 mm dyneema for tying the sail to the spars. This allows you to take a couple of turns through the eylets and the holes in the spars, making it easier to tension it.

3. Same as 2.

4. Probably more downhaul (better pulley system without taking the line over the top of the boom but rather hanging the pulley system under the boom.

Best regards,

Joost

Originally Posted by Joost

4. Probably more downhaul (better pulley system without taking the line over the top of the boom but rather hanging the pulley system under the boom.

Best regards,

Joost

Thanks Joost for the suggestions.

I am now hanging the pulley from under the boom, and I get a lot of purchasing power, it seems.

Howdy, Grant is probably right ... it sounds like a classical overbending crease. AS he says there are two aspects to it. Either the boom is bending and there is not enough curve cut in the foot of the sail. A stiffer boom would fix it and is probably easier than replacing or recutting the sail. It does sound like most sailmakers are providing enough curve. If someone has this problem and doesn't want to replace the boom they can use some carbon fibre tow or unidirectional carbon to reinforce the boom A little would go quite a long way. MIK

Oh darn more projects.

I just wanted to sail already.

Perfection is not required. It is actually the enemy.

Originally Posted by MiddleAgesMan

Perfection is not required. It is actually the enemy.

Exactly!!!!

Just get the bits and wait until some bad weather is forecast!!!!

Keep sailing. You will gain 10% from going sailing regularly as opposed to the 0.05% of getting rid of the crease.

Just a thought ... does the crease go down to a particular tie point on the boom? Release that one and see what happens. It could be the eyelet is a bit out of line. (ha ... just realised I am quoting Grant. If it works give him the credit!)

MIK

Originally Posted by callsign222

(Before people start squawking my downhaul has since been changed, this is a picture from the maiden voyage...)

It seems they squawked anyway!

Originally Posted by Boatmik

Just a thought ... does the crease go down to a particular tie point on the boom? Release that one and see what happens. It could be the eyelet is a bit out of line. (ha ... just realised I am quoting Grant. If it works give him the credit!)

MIK

My crewmember who's only experience is in Sunfish mentioned this underway as well. I threw out my back yesterday morning getting out of bed so no sailing for me for a few days but no work either so I'm thinking of lacing the foot of the sail and messing with the outhaul today to figure it out good. If you notice, the re-enforcement bottom strip on the boom does not extend to the front, I might scarf on an addition piece to beef this area up too. Maybe my back is a blessing in disguise so I can optimize the rig, but I'm really missing out on some epic sailing conditions right now-- bright sun, 15-20+kts, and 75F/24C .

Stupid back.


And this is the strangest emoticon I think I've ever seen. Who's running this place?