Thread: Strange question -- GIS

Hello Sam.

When sailing with your son, how about just tying in a reef and then raising the sail high enough with the halyard to maintain generous boom-to-skull clearance?

Grant

Howdy,

Weird questions are often the good ones.

Old Yeller has the best idea, I think. Put one reef in and set the boom a bit higher - but not too much.

The boomless setup really is a dipping lug setup. The way they used to be tacked was to drop the sail and pull the lot around to the other side of the mast and rehoist.

Not easy. If you don't do this the boat will be really unstable on the "wrong" tack.

If someone ever broke their boom it might be quite a possible way of sailing back, but I would probably put a reef in (moves the clew - the back edge of the sail forward) and move the traveller as far back as possible to try and get a reasonable sheeting angle.

I think the foot will be too full to get really good windward performance but might be able to limp home. The other problem is the common one with other boomless rigs ... the sail shape goes to pot when the sheet is eased becoming too full just as you want to get rid of power when you ease the sheet in a gust

Best wishes
Michael

OK. Sounds like sailing with a reef in is the best idea. I did read some about the dipping lug...sounds like a real pain in the neck.

The reason I got thinking this way is that several entry level Hobies have boomless sails. I guess the fact that the cloth isn't laying across the mast makes a big difference. But I would think the issue Mik brings up (the foot being to full and hence difficult to de-power in a gust) should be an issue for them too.

Ross Lillistone's Phoenix II (or is it III?) also has a boomless sail. DOes anyone have any experience with that boat?

Thanks,

SamMilo

Ross's boat has a number of rig options included in the nice plan.

The principle is that if the sail twists and becomes too full as it is eased then it is not very efficient, whatever the rig arrangement.

I really think it is only suitable as an auxiliary rig for a canoe or a rowboat that is mostly paddled or rowed and a cheap, simple and easily stowed sail and rig is required.

You don't see any real performance catamarans without booms except for those with curved traveller arrangements and also very high apparent wind when they head downwind.

So here is an efficient A-class cat without a boom - I think. No ... it does have a boom ... I know some of them have no boom and a highly expensive curved traveller. I think the one below has decided that a boom is cheaper than the traveller! But some don't.



And here is the inefficient bag of the Hobie below. The more you ease it the worse it gets no matter how enticing the model on board. This pretty bad for an upwind shape, particularly on a multihull. Wonder if a PDRacer would burn it off upwind?

I see. I think. It sounds like you are saying the performance is pretty pathetic on the majority of boomless rigs (esp. those without curved travellers). I love the performance of my GIS especially when I have another adult on board to help with some more weight. But like I said above, I'm trying to figure out a nice way to take my 5 year old son on a day sail.

It seems the easiest thing is to just reef the sail. *BUT* if I'm not so worried about performance, would sailing it without a boom be safe. Or would it lead to some serious instability? If you think it is only a performance issue then I may try it...

It seems one of the threads (GIS handling maybe?) the author is sailing witha loose footed sail but still a boom, would that experience some of the lousy sail shape upwind that the Hobie Bravo in the picture has?

Originally Posted by SamMilo

I'm trying to figure out a nice way to take my 5 year old son on a day sail.

Blimey, he's got to learn to duck! Or make him walk the plank! Or maybe keel haul him (easy enough with small kids).

He'll only forget to duck once or twice, okay maybe 3 times, some kids are hard headed.

Put some pipe insulation foam around the boom.

Or even better - you be the crew/ballast and promote him to captain & leave him in the back to drive!!!!

Arrrrrrgh,
TomH

Thanks Tom for the pirate sounds!

It must be close to international talk like a pirate day again!

But Tom is right ... there are thousands of booms passing over peoples' heads at this very second - it is not a big risk of serious harm.

The ducking for the boom can be part of the fun of sailing with a 5 year old

"Duck and watch the boom go over your head, then you can come up again" And then give him a warning each time you tack or gybe like you should when there is someone sailing with you. It will be part of the game.

I would probably still put a single reef in the sail and set it with the boom a foot higher than normal - that is a long way up - but still train your 5 year old to play the "Duck and watch the boom go over" game.

It teaches the correct responses so he learns (without realising) to take responsibility for making sure that the boom is out of the way.

Just like the best way to teach a kid to balance on a bicycle is not to use training wheels but to take the pedals off so the child can push themselves along with their feet. That way might have a little extra risk of a minor fall but will teach the child the right co-ordination skills.

Something they don't get if you try to protect them from physics with training wheels.

So I think ... take the precaution of raising the boom, but teach him the right response to your call of "duck" and teach him to use his own eyes.

Best wishes
Michael.

Yep, proper training is the way to go. Tell him if he lets the boom hit him in the head even ONCE he's going to have to wear that dreaded bicycle helmet for a full year.

Fair enough. Sounds like consensus is to avoid a boomless set up and just get him to learn the art of ducking.

I tried another thing this morning: I moved the block on the yard that the halyard passes through about 1-1.5 feet down. This lets the yard get hoisted quite a bit higher...but what should I be worried about? The shape of the sail in my driveway looks great.

I know the design is the way it is on purpose and it's well thought out and all that...

SamMilo

Originally Posted by SamMilo

The reason I got thinking this way is that several entry level Hobies have boomless sails. I guess the fact that the cloth isn't laying across the mast makes a big difference.
SamMilo

the so-called boomless cat sails make up for it with many battens.
They have a large, full-length one near the sail foot, and in very stiff sailcloth.
cheers
AJ

This morning I raised my sail in my driveway and made a couple of measurements.

In a previous post I mentioned that I moved the halyard block down a little on the yard. I believe the plans call for that block to be placed at the midpoint of the yard. Well to position it originally, I counted the grommets on my Duckworks sail, 9 of them. Then I lashed the block to the yard through the 5th grommet. When I raise the sail like this I get the front of the boom just about 200, 220 mm above the sheerline (depending on my downhaul).

Yesterday, I moved the block on the yard down one grommet. So now there are 6 grommets up to the top of the yard, and only 3 down to the bottom. when I raise the sail in this configuration the shape looks nice, but now I have around 420-450 mm above the sheerline.

I'm planning a day sailing on Sunday and really hope that moving the block the way I did won't cause any unusual behavior or bad stresses on the boat (mast in particular). By the way, I have the hollow box mast.

SamMilo

As MIK likes to say, it's not the sail area that can over-stress a mast in a small boat, it's the amount of live ballast on the rail. Moving your sail up higher just increases the lever arm working to heel the boat over. Unless you offset that with another heavy adult on the rail your mast is not being stressed any more than it was before.

I did not use the grommets to attach the yard block. Mine is simply lashed near the midpoint. Something about using the grommets bothers me but I can't say why. It's just a gut feeling so it's probably OK.

For my first year of sailing the boat I didn't run the block through a grommet either. Just recently as I was messing with the rig though I noticed a slight amount of slippage on the block. This seemed to cause the boom to be lower than recommended...hence the block through the grommet.


Thanks for the replies. I'll give it a try tomorrow and see if the higher sail is as much fun as the standard rig.

SamMilo

The mast will have no problem SamMilo.

When playing with the sail it is fairly important to keep the halyard about halfway along the yard.

The sail needs to keep the right balance of sail in front of and behind the mast and the right amount of boom in front of the mast as well.

This all helps keep the centre of the sail area in the right position relative to the centreboard. There are other configurations that might work if you know what you are looking for, but the safest ones are the settings I've given in the rigging and tuning page.

Set up and performance of lug and sprit rigs and rigging for small boats

If you know what you are doing regarding the self vanging and the centre of effort relative to the centreboard then it is possible to play around with different configurations. But the standard method is the safest.

MIK