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Go Back   SailNet Community > On Board > Gear & Maintenance > Boom rise with reefing... How much?
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Thread: Boom rise with reefing... How much? Reply to Thread
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Topic Review (Newest First)
02-07-2013 06:58 PM
Faster
Re: Boom rise with reefing... How much?

The booms need not be parallel.. there are plenty of examples of otherwise, including the majority of the ocean racers as your picture shows. In the 70s and 80s booms 'drooped' substantially as some extra unmeasured sail area was snuck in there by lengthening the leech and dropping the clews. (often an issue trying to fit a dodger onto an old IOR racer)

I think, esp for ocean sailing, there's some merit in raising the clew relatively as you reef, it can avoid tripping the boom in a wave.. for most of us coastal sailors I'm not so sure it's an issue. Having a sail with a routinely 'lifted' clew might create some extra headroom and avoid the >BOOM< of an unintended gybe on certain boats with limited boom clearance.
02-07-2013 06:45 PM
casey1999
Re: Boom rise with reefing... How much?

Reading all this with interest.

I was having the opposite problem, when both reefed and not reefed, my boom would droop, and I could not get the main sail haylard to tension the sail using that haylard alone. I need to have the raise the head of the main sail high, then pull the Tack of the sail down with the cunningham. This would both tension the main sails Luff and lift the clew to make the boom parallel. For some reason, no matter how much tension (or fear of breaking somthing), I could not get the sail luff to tension unless I used the cunnigham. When using the cunningham I could put low tension on the main sail's haylard, but provide most tension by using cunningham. Maybe play with the cunningham and main haylard to see what it does to

Here is a question:
Why does the boom need to be parallel? I would like to modify my sail by raising the clew to boom connection up by about a foot (I have a lose foot main). This would allow the boom to clear my head, and I doubt would negatiely impact performance much. I see a lot of open 40s and 60s with angled booms like this. Pros, cons?

Regards
02-07-2013 12:10 AM
lancelot9898
Re: Boom rise with reefing... How much?

I always thought that you wanted to do Step 6 before 5 because of the stress that would be put on the sail slugs if you did it the other way.
02-06-2013 11:48 PM
Faster
Re: Boom rise with reefing... How much?

Looks like the right sequence... don't really think it matters whether you do 5 then 6 or vice versa.

The only way your boom can rise as described, really, is that the line from the reef tack to the reef clew is not parallel to the foot of the sail... So it is what it is. If you feel it's 'odd' or wrong or you don't need it, have the new sail made differently.
02-06-2013 11:42 PM
MedSailor
Re: Boom rise with reefing... How much?

Quote:
Originally Posted by fallard View Post
You didn't mention easing the main halyard to allow the reef tack to come down to the boom as you haul in on the reefing line(s). If you have jiffy reefing or single line reefing, this would explain why your boom is pointing to the sky.

So, the question is: are you bringing the reef tack down to the boom when you reef?
Here is how I reef.

1. Head into wind.
2. Release mainsheet
3. Lower halyard (topping lift supports boom)
4. Attach tack hook at gooseneck to new reef tack on sail at first reef

5. Crank in on jiffy reefing line until first reef clew meets boom (boom rises)
6. Raise halyard to take out slack

7. Bring in mainsheet
8. Resume course and trim appropriately

I put 5 & 6 separate because now that I think of it, I can't remember for sure which one of those I do before the other.... I'll have to go reef at the dock this weekend.

MedSailor
02-06-2013 11:33 PM
MedSailor
Re: Boom rise with reefing... How much?

Quote:
Originally Posted by RichH View Post

So first, the pregnant question becomes, how much rake do you normally carry in that main mast? That approx. rake angle will be needed before I can give a reasonable 'guestimate' reply and one based on generalized 'sailmakers data' for the F41.
Not exactly sure how to measure rake to be honest, but I got a lot! Weather helm and balance be damned, it sure looks cool! I'd say my rake is in line with the line drawings, so lets call it 7 degrees

Quote:
Originally Posted by RichH View Post
Id need to know the construction of the mainsail ....
.... woven dacron sail cloth?
It's a lee sails sail, so yeah it's dacron-ish.

Quote:
Originally Posted by RichH View Post
.... does this sail have a luff bolt rope (a three strand dacron rope inside a 'sleeve' at the luff?
could even be that there is an 'exposed' three strand 'rope' sewn directly to the luff ... yes/no?
The sail does have an exposed 3-strand bolt rope sewn on the luff but it also has sail slides that go into an internal track.

Quote:
Originally Posted by RichH View Post
.... What is the luff length of the sail (my data book omits the F41)?
I=47 J=16 P=42 E=17 PY=24 EY=11
One caveat here is that my masts are aftermarket aluminum spars made by Spartech if I recall. The mizzen has different stay/shroud arrangements than standard and I don't honestly know if they're taller/shorter than stock. They "look" to be the same as other formosas and I don't think they're off the standard measurements by much if any.

Quote:
Originally Posted by RichH View Post
.... How old (yrs.) is this sail?
Really old methinks. It was blown out and baggy when I bought the boat in 2007 and it had been for sale for 2 years. Previous owner sailed San-Diego to Alaska and PNW often.

Quote:
Originally Posted by RichH View Post
.... and how much 'extra strain' do you add to the mainsail luff when 'raising' this (dacron?) mainsail?
.... if you don't 'stretch out' that bolt rope, explain briefly how you raise that mainsail.
Well I used to "just raise" it but after reading an excelent treatise of yours on "how to hoist an old mainsail" I now raise the sail as follows:
1: hoist sail until halyard is at the top of the mast and the luff has no wrinkles.
2: take a few extra turns on the halyard winch and continue to crank until one of three things happens:
1. I get a new hernia.
2. I break something expensive.
3. I pop a blood vessel in my eye.

Having said that, the reefing I did that caused the boom (which is level when the main is hoisted without reefs) to rise with reefing was back when I was "just" hoisting the mainsail without the extra cranking.


I'll be at the boat this weekend for pictures, since y'all have asked. Assuming it's not blowing hard at the slip I'll post what happens with the reefs. Any particular photo requests that would help in figuring out what is going on here??

MedSailor
02-06-2013 04:12 AM
mdbee
Re: Boom rise with reefing... How much?

02-06-2013 01:18 AM
fallard
Re: Boom rise with reefing... How much?

Quote:
Originally Posted by MedSailor View Post
Hmmm.... Good point. I don't have a boom jack, but I do have a topping lift that I rarely adjust. When I put a reef in I have to let out a bunch of mainsheet and then as I pull the reefing line in the end of the boom lifts up to meet the new clew.

Then, when I shake out the reef I let the reefing line out slowly and the boom comes back down. Were I to loose control of that line it would "fall" back down to horizontal where the topping lift would catch it.

Perhaps I should phrase my question differently:

Is there any reason that I shouldn't just have the sail built so that the boom stays level with each reef?

MedSailor
You didn't mention easing the main halyard to allow the reef tack to come down to the boom as you haul in on the reefing line(s). If you have jiffy reefing or single line reefing, this would explain why your boom is pointing to the sky.

So, the question is: are you bringing the reef tack down to the boom when you reef?
02-06-2013 12:34 AM
RichH
Re: Boom rise with reefing... How much?

The Bill Garden design Formosa 41 originally had quite a radically raked mainmast ... looks like up to 7 degrees of rake on the 'spec'. drawings. Many of such radically mast raked boats from that era now usually have their masts 'straight up' for 'sail/helm balance' considerations ... and if now carried more 'straight-up' will radically/directly change the boom angle.

So first, the pregnant question becomes, how much rake do you normally carry in that main mast? That approx. rake angle will be needed before I can give a reasonable 'guestimate' reply and one based on generalized 'sailmakers data' for the F41.

Id need to know the construction of the mainsail ....
.... woven dacron sail cloth?
.... does this sail have a luff bolt rope (a three strand dacron rope inside a 'sleeve' at the luff?
could even be that there is an 'exposed' three strand 'rope' sewn directly to the luff ... yes/no?
.... What is the luff length of the sail (my data book omits the F41)?
.... How old (yrs.) is this sail?
.... and how much 'extra strain' do you add to the mainsail luff when 'raising' this (dacron?) mainsail?
.... if you don't 'stretch out' that bolt rope, explain briefly how you raise that mainsail.

Two things possibly going on here that I can 'guesstimate'; but, I would need some/most of those questions answered before giving my 'best guess'.
If this sail is a bolt-roped woven dacron sail, and is more than about about 3-5 years old and the sail has seen a LOT of use .... probably its not the angles that the reef positions are making but rather your boltrope in that mainsail 'may' be grossly shrunken, the luff length is now MUCH shorter than when 'new' and as a result the boom 'may' be drooping at the aft end, giving the appearance of being 'normal'; BUT, if the mast is no longer raked to the OEM design the boom may be giving a 'visual' cancellation, etc.
This is quite complex; but, the amount of rake in that mast is the key here on what is exactly happening - as you SEE it ..... Plus 'how much strain' you are adding to the halyard .... AFTER that sail is 'just up' when raising.

My first suspicion is that your mainsail luff has shrunken over time (quite common on aged boltroped sails) and the dissimilar shrinkage of that bolt rope is the reason for the apparent different 'visual' angles you see when 'full up' or when reefed. When raising this mainsail you probably winch the halyard so that the sail is 'just up'? correct?

:-)
02-05-2013 08:03 PM
MarkSF
Re: Boom rise with reefing... How much?

My attitude is this :

When you reef, you lower the centre of effort of the sail, a lot. Therefore, it's OK to allow it to rise again just a little bit by having the boom higher. It's less likely to hit you on the head, to catch in the water, everyone's a winner!
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