boom height and effect of flying a smaller main.

ghostwriter247 · Post by **ghostwriter247** » Thu Feb 24, 2011 6:43 pm

Does anyone have any insight into how far from the base of the mast the boom height should be on a bristol 27? I've looked at pictures online and it looks like it actually is above the sail slot gate which is only 18 inches above the base.

What would be the effect of making a main sail smaller to get the boom out of the cockpit? I know it needs to be there to balance the headsail, but on these boats the headsail is the main driver of the boat yes?

Does anyone have experience sailing these models? They tend to reef early anyway like a triton correct?

If thats the case why not shorten the main sail a couple feet and raise the boom a bit in the slot.

Ive seen some list the bristol sail measurement as 28 and some as 25 for the luff and was wondering if this was why.

I'm going to order my main sail and mast track early next week and trying to finalize the size.

Thanks

Josh

Hirilondë · Post by **Hirilondë** » Thu Feb 24, 2011 7:19 pm

This is what I found searching for the sail plan of a Bristol 27. I am not so sure I would want to change the dimensions of the main all that much from the design. The last modification I would make would be to raise the boom. I reef a lot on my Renegade, and find the boat very balanced doing so. But the forces are lowered reefing, not raised. And the slot does not change much lowering the peak, where as it would be changed considerably raising the boom.

Do you find the boom intrudes that much on the cockpit?

ghostwriter247 · Post by **ghostwriter247** » Thu Feb 24, 2011 7:30 pm

Overall its not so much whether i raise the boom or not. Being able to sail with a bimini up would be nice tho. Really it was the discrepancy in the luff length I've seen on line.

From the top of track to the top of the sail gate is 29 foot 2 inches and the gooeseneck is about 3.5 inches so the room is there for the 28 foot luff length listed on the sail plan.

I had heard that they reef early and just wondered if that was why some sail lofts listed the luff at 25.5 for this boat and if this was a good option overall.

Bacon quoted at 25.5 luff and national at 28.

jollyboat · Post by **jollyboat** » Tue Mar 01, 2011 10:28 pm

It appears that Bristol offered the 27 with two rigs - a standard and a tall rig.
Bristol 27 I 30.5' J 10.3' P 25.5' E 12.2'
Bristol 27 Tall Rig I 33' J 10.3' P 28' E 12.3'
When you measure the max hoist on your boat you will know what rig you are dealing with, standard or tall.
The dimensions that you need to measure on your mast for the new main are the max hoist, measured from the measurement band at the top of your mast, (if you have one) to the tack pin location and the max outhaul, measured from the tack pin location to the max outhaul position on the boom. Your sail maker will also want to know as many details about your rig as possible, especially due to the age of the boat and the many changes that owners make to stock rigs over the years from owner to owner. You will need to establish what size and type the luff and boom hardware is. The boom may only have a bolt rope in which case you will need to determine what size bolt rope should be used or if you want to have a loose footed main. You will need to record where the gates are for both the main and boom as well as the tack pin set back measured from the back face of the mast. If your boom has an outhaul car you will need to measure and record where the track starts and measure it's length as well the max height of the outhaul car from the top of the boom extrusion. You will also need to measure and record where the reef blocks are on boom measured back from the tack pin. Make a note of what kind of tack pin arrangement you have, some use a shackle and others a pin that is part of the goose neck casting. I lash my tack with line, yours may be different all together. In concern to your question of boom height, if you have the sail plan, you can put a scale ruler on it (any plan) - determine a scale, measure the plan and come up with pretty damn close idea of where the boom should be. There is often a measurement band on the mast at the tack position too and if your have one on your mast that is presumably where the forward boom height on the mast should be. You also mentioned something about the boom being in the cockpit - that is troubling to me. That does not sound right at all. Properly rigged with a properly fitting main on the B-27 should allow plenty of room in the cockpit when the boom wipes across. I don't know what the culprit is in your case. I suspect a very tired sail. When you get your new main, check your rig to be sure it is properly tuned. If you do not have a tuning guide you can start with the guide that is available for the Triton and work from there. Most importantly your mast should be exactly straight up and down and not favoring one side or the other. If you are experiencing lee helm your mast may be to raked aft to help correct this and if you are experiencing weather helm*, (in moderate breeze where all sail should be able to be flying), you might rake the mast forward but as often as not, simply making sure that your head stay tension is correct will do wonders to help with weather helm on these designs. Alberg's designs are especially susceptible to weight. (too much gear on the boat) and in the wrong place, do not use the ends of the of the boat for storage - and rig tuning (sails are a HUGE part of the last equation as it is with most sailboats) I hope this helps. Rachel and Tim might have some suggestions too.

Rachel · Post by **Rachel** » Tue Mar 01, 2011 11:17 pm

jollyboat wrote: Rachel and Tim might have some suggestions too.

Thanks for thinking of me, but this is out of my knowledge area -- when it comes to rig and sail changes. I do agree that it's nice if you can reasonably make it so that the boom is above your head level when standing in the cockpit.

ghostwriter247 · Post by **ghostwriter247** » Wed Mar 02, 2011 2:22 am

I went to the boat the other day and took some pictures so from the top of the track shown here
http://crossedimages.com/Other/The-Celt ... 3529_aq4jx

Measuring where it terminates below the slots for the sheave to the top of the mastgate is 29 foot 2.5 in. the mast gate is six inches long and from the bottom of the gate to the base is 12 inches. You can to a certain extent you can see the wide spot which is the gate here
http://crossedimages.com/Other/The-Celt ... 3261_ZgknJ

the top of it is at the same height of the 2nd highest cleat.

You can see the gooseneck here
http://crossedimages.com/Other/The-Celt ... 3456_zVrrW

Its height is 3.5 inches.

To complicate things the mast is still down with the boom off for transport and it was taken down before i picked it up so I dont have any pictures of it prior to it coming down without the sail cover obscuring.

There are some with it in the water here. http://crossedimages.com/Other/sailboat ... 3775_F4JMs

I would post one or two but i can't seem to get them small enough to post.

So the only thing i can figure out is that the boom would be above the mast gate, but the dimensions of the sail are still open to interpretation. I guess Technically a 28 foot sail would fit with the boom under it, however am concerned it should actually have the 25.5 luff.

I am putting in a strong track system as well so that helps in terms of knowing the attachment of the luff as i am ordering both through dirk at national sails.

So pretty much just left trying to figure out which size to get and i can go ahead and order.

I could measure my old sail as i will be down there tomorrow. I'm pretty sure its the original.

The boom actually used short wood dowels if i remember correctly as slugs.

Josh

ghostwriter247 · Post by **ghostwriter247** » Wed Mar 02, 2011 11:49 pm

I measured my sails and the luff is 26 foot 3 in and foot is 11 foot three. So i guess it originally had the tall rig setup.

The foot is a bolt rope so unless anyone advises against it will probably go with a bolt rope foot again.

Post by **Tim** » Thu Mar 03, 2011 7:48 am

Bolt ropes on foots are a real pain. They make the sail hard to install, and tough to adjust the outhaul.

Consider a loose foot instead.

Figment · Post by **Figment** » Thu Mar 03, 2011 1:00 pm

Also, while the cloth stretches over time, the rope shrinks, exacerbating the baggyness of age.

forrest · Post by **forrest** » Fri Mar 04, 2011 3:58 pm

Just to add my probably useless anecdotal evidence...

I have a Pearson Renegade which some previous owner put a dodger and a smaller main on. So the main I think is almost a foot above where it should be. It looks a little less cool than it should, but it sails fine. It still balances out really well. And as a bonus I rarely hit my head on the boom.

Forrest

jollyboat · Post by **jollyboat** » Sat Mar 05, 2011 12:07 am

It looks ok to me. I would bet that you have the standard rig. It looks like the main would be bent onto mast via the gate and then the gooseneck of the boom is installed and either slid up and the gate closed with a "locking gate slug" or the goose neck is slid down from the gate and the gate locked from above the boom; the latter making the most sense for use of a down haul. Some boats do not use a down haul and rely only on the main for halyard for luff tension. Definitely a lower boom position than that of the Triton without question. There appears to be plenty of height in the cockpit for allowing the boom to wipe across the cockpit during tacks and jibes. The Strong Track System is a great system and I am sure you will like it very much. In concern to the foot of the main being affixed to the boom via a bolt rope or to opt for a loose footed main I agree with the two suggestions that favor a loose footed main. Sail control is greatly improved with a loose foot and stowage is no more demanding than it would be if you had the foot affixed to the boom with a bolt rope especially with the enhanced performance of raising and lowering the main with Strong system.

ghostwriter247 · Post by **ghostwriter247** » Sat Mar 05, 2011 1:31 am

Ahh it was a good day at the boat!

Once i sat down and called dirk at national sails ( a shameless plug I know but he has been great) I got my sail ordered, and yes looks like a standard rig.

My thanks to gary for weighing in on his boom height for me it really made things easier.

I did wind up getting fully battened main with three sets of reef points in the 6.4 oz cloth, WIth the track.

Got a great price on the track as well. Including installation of the sail hardware it wound up about $26 a foot for those considering the upgrade. Which is a lot less than a lot of people are selling just the pieces

An now on to the exciting news!

So when I first unpacked the sails I found two new headsails i wasnt expecting. Since it was a bargian price I figured everything was shot so didnt look too much beyond a sound hull, deck and boom as well as other structural stuff.

Today I Decided i would try out the Cockpit mounted whale gusher manual bilge pump and it worked great so score two.

I had looked at the forward through hulls and they were the old style originals so i didnt bother to check the cockpit drain through hulls. When i did poke around today I found they were actually two new looking conbraco apollos and they actuate as well. So score three.

It was a good couple days off.

jollyboat · Post by **jollyboat** » Sat Mar 05, 2011 11:24 am

Josh, that is great news. Congrats on your new sail order and I am glad that you were able to put some of your concerns to rest. The PC forum is great place to a lot questions on the table for discussion. I am glad to know that you are enjoying the thrills of new boat ownership and hope that you will have some great tales of adventure to share with us in the upcomming sailing season.

Quetzalsailor · Post by **Quetzalsailor** » Sat Mar 05, 2011 6:27 pm

Those of us who are 'height challenged' in the good direction sympathize with the idea of raising the boom. Really, unless you're racing and the idea of efficiency at each end of the airfoil is important, I doubt you'd loose much. After all, our little boats with dodgers and cabins are a pretty sloppy approach to airflow as they are.

Quetzal's boom ends right at my head when it's amidships; it just clears the dodger and the boom vang is a pretty poor angle since the it's so low to the cabintop. But, hey!, it's that CCA look, so I'm not changing it.

You wanna' sail a boat whose boom is just about on deck, try a Finn! Just about the most miserable boat I've ever sailed between the repeated head-bonking and the pain in the knees and shins from hiking.

ghostwriter247 · Post by **ghostwriter247** » Sat Mar 05, 2011 7:17 pm

yeah that doesnt look like fun, but it builds character Im Sure.

I just measured my big headsail that looks new and it looks like its for a much bigger boat so off to the classifieds section for it.

The other is storm jib sized with triple stitched construction and like i said not used at all.

So looks like i will have to buy a new headsail too. Its a rough life.

Rachel · Post by **Rachel** » Sat Mar 05, 2011 9:01 pm

Quetzalsailor wrote:Those of us who are 'height challenged' in the good direction

Hmm, I didn't realize there were "good" and "bad" directions....

ghostwriter247 · Post by **ghostwriter247** » Tue Mar 08, 2011 2:45 am

so a question on headsail sizing. outside of having a spinnaker what are your preferences for a light air hanked on headsail?

Would you get a 150, 160 or less? Assume there is a 110 or 120 for when the wind comes up.

What weight cloth would you use? Any features you would build in to it? Partial battens?

How many knots of wind would it be useful up to?

Would you go with a heavier weight large headsail you can reef or just do changes?

Were asymmetrical spinnakers designed to replace the really big headsails?

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