Main boom

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Main boom

Postby Brian » Tue Dec 02, 2003 4:12 am

I have an 1980 38 MKII.
Has anyone had experience with remounting the main boom higher on the mast? I am seriously considering this for several reasons.
1) Get it above my head ;-)
2) Gain more room for a dodger. Any comments are welcome! Brian brian.bennett@sdccu.net
Brian
 

Re: Main boom

Postby Stephen Carstensen » Tue Dec 02, 2003 4:21 am

The center of effort will be higher. Causing (for the same sail area) a more tender vessel. Secondly, there will be less mainsail area unless you are willing to do what it takes to correct that. Less sail area is going to effect the balance of the boat and the helm negatively (assuming it's correct now). If you are bent on doing it (and I understand why) area you considering a full batten main, or some other way to increase the roach (or whatever) to recover the lost sail area? If not, don't raise the gooseneck. just put in what racers call a flattening reef about a foot up the leech or have the leach cut a little shorter. That way the total sail area lost will be less. I am not a sailmaker and this is just from personal experience only... - Steve warmrain@rockisland.com
Stephen Carstensen
 

Re: Main boom

Postby Ken W. » Tue Dec 02, 2003 4:27 am

Two things to consider: Can you still get full hoist on the sail or will it need to be recut. Will the end of the boom still clear the backstay at all vertical angles (accidental jibe) Ken kc8pql@arrl.net
Ken W.
 

Re: Main boom

Postby Brian » Tue Dec 02, 2003 5:08 am

I am not sure I fully understand the last suggestion of the flattening reef. Granted, if I do shorten my main, the CE will also go up. I figure it will go up approximately 2/3 the height. So if I raise it 18" then the CE will go up 12". With Dream Catcher weighing in at 30k w/ 10k of iron underneath her, I am not convinced the difference will be all that noticable. Also, with reduce sail area there will be less force at the new CE. The big question is - can I live with less power? I may be wrong. So, has anybody done this? Brian brian.bennett@sdccu.net
Brian
 

Re: Main boom

Postby Brian » Tue Dec 02, 2003 5:11 am

I'm thinking recut.
Good point about the backstay. Hmmmmm. Shorten the boom if necessary I suppose. Thanks!
Brian brian.bennett@sdccu.net
Brian
 

Re: Main boom

Postby Stephen Carstensen » Tue Dec 02, 2003 6:18 am

Not just less power, but different balance. The flattening reef will raise the clew without shortening the luff. Allowing more head room. Or just recut the sail, leaving the gooseneck where it is... - Steve warmrain@rockisland.com
Stephen Carstensen
 

Re: Main boom

Postby Stephen Carstensen » Tue Dec 02, 2003 6:20 am

Yes, and further reducing main area. You've got to really think this through Brian. I too had the same desire, and was talked out of it by my sailmaker and good freind - and it wasn't easy for him to do. Now I'm thinking that I need more main not less - though the 33 is a little short on main from the beginning anyway...
- Steve warmrain@rockisland.com
Stephen Carstensen
 

Re: Main boom

Postby Kim Efishoff » Tue Dec 02, 2003 4:01 pm

Two solutions:
(1)When someone yells, "duck!", don't stand up on the cockpit seat looking for waterfowl, or;
(2)dig a deeper hole in the cockpit. Seriously though, recutting the sail to raise the boom end while leaving the gooseneck attachment at the standard hight sounds interesting. I wonder if anyone has tried this. Of course, as discussed, raising the center of effort for the mail sail will reduce the boat's overall stability. It's not good enough to just say, "raising the center of effort 12 inches won't have that much of an effect". You need to do the calculations, and you need to understand what your answer means in terms of ships' stability (raising the center of effort 12 inches can have a significant effect). And, as mentioned, balance is a big concern: you don't want to be fighting the wheel all day in order to sail a straight line. Of course you could go to a smaller headsail; but now your talking about new sail and/or modification costs, less power, less stability, balance adjustments...it's starting to sound like this solution, meant to offset a minor inconvenience (avoiding boom-head contact)is creating more problems than it was meant to correct. Back to solutions(1) and (2) above...or, you might consider a boom brake. Kim kim.efishoff@oak.doe.gov
Kim Efishoff
 

Re: Main boom

Postby John J Graham » Tue Dec 02, 2003 6:12 pm

Brian
I have an 1981 MKII S/V Cracler Box. Like you, in preperation for going cruising next year, I am replacing the Dodger and having a Bimini built in January of 2004. Both issues were discussed with the canvas maker, ie, raise the boom, cut the sail, raise the boom gallows as a way to gain room for the bimini as the boom is very long on our style of HC.
I discussed cutting the sail with my sail maker, and his reponses was "at your weight, you need more sail not less, don't do it." Last year when I hauled out I had the yard weight the boat. 37,500 lbs! and I have only about half the gear on board.
Again, I spoke to the boat yard about doing the cutting of the boom. Again, the cost was high. I also talk to the metal shop that is making the frame for the bimini, and he said "that having the tail wag the dog" Ok, so what is next on this adventure? The solution I have settled on is this, We will build the bimini without doing any of the above silly things and allow the boom to swing under neath it. We will have to remove the connecting canvas between the dodger and the bimini before sailing.
In the alternative, I have seen another HC 38 S/V Tillie out of Portland, Ore. that is docked over in Grand Marina, in Alameda, Ca. He raised the boom gallows, cut the boom and raised his topping lift very high (just short of dumb looking) and had a full enclosure put on. My Canvas maker did the job on Tillie as well, hence his suggestions to me. Perhaps, if you are not in a hurry I will post my solution here on the web.
Given the below discussion on softening of the boat, ie, tenderizing her, from raising the goose neck, most cruising will be done in 10-15knts of wind. I guess what really needs to be addressed is your intended plans. What are your long term plans? Going cruising, think again. But if you do not plan any great ocean trips. Go ahead. So much for my humble opinion.
73 de KF6SDV John
S/V Cracker Box
Oyster Cove Marina
South San Francisco CA graham7@ix.netcom.com
John J Graham
 

Re: Main boom

Postby Lewis Whitesell » Tue Dec 02, 2003 9:51 pm

I seem to remember some discussion of older HC38s having some difficulty with weather helm and I think it was the case as of 1980, before they moved the mast forward.
Brian, do you have a weather helm problem? If so, this could possibly help some with that. I think that of all of the suggestions, Stephen's shortened leech sounds like the simplest and the one least likely to seriously affect your balance. The flattening reef could also allow you to try the new configuration without doing any more modifications other than having a reef cringle installed on your main. There would also be no concerns about conflict with the backstay. Good luck, "stretch"
Lewis
Lewis Whitesell
 

Re: Main boom

Postby Stephen Carstensen » Tue Dec 02, 2003 11:08 pm

You see my main came from UK Sailmakers with a flattening reef cringle so it was an easy trial. It works so well and requires such little actual reduction (just a couple inches) that I never have modified the sail. Don't forget that a little weather helm can be a desirable thing. The only reason one of my closest freinds is here to tell his tale is because after he went overboard (single-handed) the boat slowly came head to wind and drifted back down on him. Of course too much weather helm just work the A/P, vane and crew too much and isn't necessarily efficient. The HC33T has too little main and struggles to not have leeward helm. The good news is that you can balance the yacht so that there is no helm at all. But after years of experiencing just a little weather helm (on my other sailboats) I feel a little uncomfortable without some. Furthermore it should not be forgotten that boats with a NACA (or other) airfoil keel (the HC33T does) need to have a some weather helm in order to "twist" the boat's heading in relation to her direction of travel through the water (the heading and the track are not equal) so that the weather side of the keel is developing "lift" and the leeward side is not. A prefectly balanced helm will not allow the yacht to take advantage of the airfoil keel shape. In fact in such a situation BOTH sides of the keel will be developing lift and therefore creating additional drag without any benifit. - Steve warmrain@rockisland.com
Stephen Carstensen
 

Re: Main boom

Postby Fred Rogel » Wed Dec 03, 2003 1:55 am

Hi Steve, I second that on the lift generated by the keel. We had a J-24 that we raced. We reworked both the keel and rudder to get what was the perfect foil shapes and what a difference it made in the boat's ability to sail closer to the wind direction. Fred Rogel
Manitou 1986 33T Sailboat33T@MSN.com
Fred Rogel
 

Re: Main boom

Postby Stephen Carstensen » Wed Dec 03, 2003 2:22 am

Yes, but you need some weather helm to take advantage of it. Furthermore on a boat like the HC33T where the rudder is attached to the aft end of the foil, the steering input to counter the weather helm actually improves the shape and efficiency of the foil by acting as a large trim-tab or flap... This may not have as much effect on a fin keel/spade rudder boat. But in that case the rudder is it's one lifting surface. In this case it really is more like a plane. Wing and horizontal tail. It's amazing isn't it, when the foils are worked to be most efficient for the given medium and speeds, many are really just airfoils. I've seen some amazing things done by knowledgeable people. - Steve warmrain@rockisland.com
Stephen Carstensen
 

Re: Main boom

Postby Fred Rogel » Wed Dec 03, 2003 1:52 pm

Hi Steve, I agree with your thoughts on weather helm. We are always adjusting the mainsheet and traveler to induce weather helm on our 33T. With the main, staysail & lapper, the mainsail boom is normally set on center line to induce weather helm in 12-15 apparant and as the wind speed goes up the traveler car is moved to leeward to reduce weather helm on our boat.
The 33T is a fast boat if you have some wind! Fred & Christine Rogel
1986 Manitou 33T
Sailboat33T@MSN.com
Fred Rogel
 

Re: Main boom

Postby Tom & Sue Friend » Wed Dec 03, 2003 3:27 pm

As Kim mentions "...recutting the sail to raise the boom end while leaving the gooseneck attachment at the standard hight sounds interesting. I wonder if anyone has tried this." That is exactly what we did to Mystique a few years ago. When we had our new main & mizzen built, we went with a full batten design that put more area higher up (bigger roach) and then we raised the boom end on the main about 4 inches. We never raised the boom crutch, and all works in perfect harmony. The rig is far more balanced and pulls to weather much better than before. A lot of this credit has to go to the new sails, as the original Lee Sails were blown out long before Mystique came into our lives. SVMystique@centurytel.net
Tom & Sue Friend
 

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