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Thoughts about reefing the main from the bottom
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Author:  KarlR [ Wed Aug 22, 2012 11:40 am ]
Post subject:  Thoughts about reefing the main from the bottom
After sailing my Bravo for a while I decided to move up to a H16, bought a old boat, referbished it, and now have it on the water. The concerns I have at the moment are these:
1) I think it is a matter of time until I smash one of my kids on the head with the boom. Probably not a long time either. I don't want to hurt them and I don't want to spoil our sailing trips by constantly yelling at them to keep their heads down.
2) Winds are pretty strong where I am, and the H16 is gonna have a awful lot of power for my current skill level.

Since I have an old boat it is set up so I can reef the main by dropping the sail, but I would like to keep the sail in place but raise the boom (to both drop power and reduce the kid head bonk factor). I can think of two ways to do this:
1) cut a notch in the mast bead on the main at the height of the reef grommets so that the sail can be run up to full height but only put into the mast slot down to the reef points. And then reef it up by raising the boom to that point.
2) cut another sail feed in hole in the mast track at the height of the reefing grommets and just feed the sail from there.

Both are pretty easy to attempt. The first one is more reversible if I don't like it as I can get old main sails for pretty cheap a quite a bit easier than I can get another old mast, but I am worried that the cord inside the bead on the main sail is not going to stay in place if I cut it and/or there will be fraying issues that will make raising the main hard if I want use the whole thing.

Any thoughts? What will go wrong? Am I just nuts?
Author:  srm [ Wed Aug 22, 2012 12:04 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
Ummmm, bad idea IMO....

You will actually be raising the CE of the sailplan if you do this, so it might have less power but will heel and pitch the same if not more. You want to keep the power low in the sail to make the boat more stable (and faster). Reef the sail the correct way and/or get a roller furling kit for the jib if you need to depower.

As far as getting bonked in the head, we've all been there and we've all learned to duck. Mabye glue a pool noodle to your boom if you're really worried about it.

sm
Author:  TarHeel 16 [ Wed Aug 22, 2012 12:25 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
Honestly, I'm not being sarcastc here, but until the kids can learn to be aware of the boom, have them wear bicycle helmets. Make it an incentive and tell them that when you see them become aware of the boom, then you'll let them take them off.

Typically, the skipper will announce the intent to either tack or jibe and wait for the crew to respond before initiating, so that may help, too.

Additionally, I prefer to keep my boom close to the center for both safety & performance. I'm no engineer, but I can't imagine how many weak points that type of alteration would make. I think your current practice of educating the youngin's is the best route.

Best of luck!
Author:  KarlR [ Wed Aug 22, 2012 1:02 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
I'm liking the pool noodle idea. I took the boat out (solo) for the first time last weekend and had the bonk issue well in mind. Still as I went into my first jibe I noticed that the rudders had come out of position (I replaced the cams, but apparently still have to do the stiffener/ shim thing) and got distracted by that and just got totally creamed in the head.
At the moment between the fact that 50% of my tacks on the 16 getting stuck in irons (I can tack my Bravo pretty much 100% of the time) and my 16 jibes are not at all OSHA approved (Bravo has no boom) there is no way the kids are coming out on the 16. Which is kinda the point.
Author:  sxrracer [ Wed Aug 22, 2012 1:39 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
when your tacking, wait until the sail starts to swing over before you change sides.
Author:  Hobie Nick [ Thu Aug 30, 2012 7:07 am ]
Post subject:  Re: Thoughts about reefing the main from the bottom
I am an engineer and I will say DO NOT reef the main by moving the boom higher on the mast. The first reason has already been stated above about the center of effort (CE) of the sail. The second reason has also been mentioned about weakening the mast. If you move your boom higher you will be exterting forces on a part of the mast that the whole system was not designed for. In lighter winds it will not be an issue. However in heavier winds (when you will most want to reef) the forces add up quickly.

To tack the H16 here is a very abridged list of steps
1) fall off slightly to gain speed
2) announce your intention to the crew
2a) move weight as far forward as possible
3) move the helm to leward (no more than 45 deg)
4) leave the jib cleated
5) as you approach dead into the wind, let out about 6"-12" of main sheet
6) let the jib backwind
7) when the main battens "pop" tack the jib
8) steer to you desired course and trim sails

It's been a while since I sailed one so if I missed something, please chime in.
Author:  56kz2slow [ Thu Aug 30, 2012 7:17 am ]
Post subject:  Re: Thoughts about reefing the main from the bottom
Nick, I find weight in the back works better than the front. When the jib backfills, it swings the bows easily while pivoting on the sterns.
Author:  Hobie Nick [ Thu Aug 30, 2012 10:33 am ]
Post subject:  Re: Thoughts about reefing the main from the bottom
It very well could. As I said, it's been a few years since I sailed an H16.
Author:  KarlR [ Thu Aug 30, 2012 1:05 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
Thanks for the input guys. I'll need to get out this weekend and try the detailed tacking approach. I was under the impression that the Jib should help pull the boat through the tack and that therefore it should be switched early. Also, being a Bravo guy, I really have no clue what the main traveller does. On the Bravo it is important to slack the main at a particular point in the tack, but I need to experiment and learn about what the 16 requires.
I am also an engineer and in my various hobbies I am always trying to design my way around my poor skills. Bad idea I know, but I also know that this is just how I am. Hopefully I will improve my tacking skills before I get too far with this idea, but I am still thinking of it. Here are my thoughts:
1) The total torque the sail makes on the hull/frame assembly is the integral of f(y)*y dy where f is force of the sail on the mast as a function of y, the height. To really plot it you would have to know wind speed as a function of y and the effects of sails shape and size and such (which of course I don't), but I will just be removing a chunk of f(y)*y from the bottom section and not adding any to the top so the the total torque should be reduced by reefing from the bottom, although not a much as it would be if the sail were dropped instead. So I think the boat will be a little more stable, and a little slower. Not as much stability gain as dropping the sail and probably a little more speed loss, but still should be some benefit.
2) I don't think the sail bead track (I'm sure there is a name for it) in the mast plays a significant role in its strength. There is a huge chunk taken out of it a foot or so down where the sail is normally fed in. The chunk I would have to take out for this could be significantly smaller since I would feed the sail in the new notch, but could still introduce the gooseneck in the old one.
3) If I am correct about point (2) and I don't like the way to boat behaves with the mod I can always just not use the new sail feed in point.
Author:  MBounds [ Thu Aug 30, 2012 4:29 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
You may be an engineer, but you're not a naval architect (I am) - and you're not understanding the forces applied to the mast by the various components.

The mast is under a significant amount of compression from the side force of the sail, as resisted by the standing rigging. The boom pushes the mast forward at the gooseneck. That's OK as long as the boom is close to one end of the mast.

By moving the boom higher, you're moving the force closer to the middle of the mast, which may put it beyond its structural bending limit. Mast under compression and pushed significantly out of column = bent/broken mast.

You're also putting the center of effort higher, even though you're reducing the heeling force by reducing sail area - the net reduction in heeling moment will probably be nil.

Reefing from the bottom is just a bad idea all around. Don't do it unless you have money to burn.
Author:  KarlR [ Thu Aug 30, 2012 5:17 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
OK. Bad idea. Got it. I'll put the angle grinder down and step away from the boat.
Just to further my understanding, though, how much force is actually transferred via the boom? I am having a hard time picturing how the body of the sail, the bead on the edge of the sail, and the boom all work together to put force on the mast. Any good literature on the subject?
Author:  MBounds [ Thu Aug 30, 2012 5:38 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
Image
It's out of print, but still available used on Amazon.

It's the definitive text on understanding the forces on sailboats.
Author:  Hobie Nick [ Fri Aug 31, 2012 8:33 am ]
Post subject:  Re: Thoughts about reefing the main from the bottom
Don't forget about stress risers in the aluminum when you modify the sail track. Unless you are really good with the angle grinder you will introduce them to the material right/very near where the boom will impart its load to the mast.

It takes practice to tack the H16 well. There is not much intertia to carry you through so it can be tricky. I suggest getting a copy of Berman's bookand reading it. It does a very good job of disseminating all the tips and tricks of sailing a beachcat. Come to think of it I can't find my copy.

When I moved into my keelboat I could not believe how easy it was to tack it. Even with poor technique.
Author:  KarlR [ Fri Aug 31, 2012 11:26 am ]
Post subject:  Re: Thoughts about reefing the main from the bottom
Ok thanks for the tips guys. Really appreciate it.
'Sailing Aerohydrodynamics' on order along with his 'Sailing Theory and Practice'. Looking forward to digging into these.

Already have Berman, but have not found it as useful as this forum for where I am right now, which is trying to figure out how to sail and right a 16 either solo, or with unhelpful small children. I'll go back and review it again this weekend. For example, when I looked last I could not find details on exactly when to move the jib during the tack.
Author:  ronholm [ Fri Aug 31, 2012 12:00 pm ]
Post subject:  Re: Thoughts about reefing the main from the bottom
KarlR wrote:
Ok thanks for the tips guys. Really appreciate it.
'Sailing Aerohydrodynamics' on order along with his 'Sailing Theory and Practice'. Looking forward to digging into these.

Already have Berman, but have not found it as useful as this forum for where I am right now, which is trying to figure out how to sail and right a 16 either solo, or with unhelpful small children. I'll go back and review it again this weekend. For example, when I looked last I could not find details on exactly when to move the jib during the tack.



This is more advanced.. But hopefully it helps you.


http://www.youtube.com/watch?v=bMka3IeyNQo
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