P16 luff and boltrope stretch

damienb

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Registered: Sep 05, 2011

Last visit: Aug 19, 2013

Posts: 24
Posted: Feb 28, 2013 - 02:48 PM

I am in the process of squaretopping a P18 sail to go on a P16. I've given the luff an extra 2" to account for boltrope shrinkage (the original sail is 30 years old), but think this might have been too generous. It has to be minimum 1" bigger to fit the head plate above the batten. I've attached a pic of my current boom-foot gap. I normally sail with about 1/2" more downhaul than this now.

Should I reduce this current gap by 1" or 2"? Does anyone know what the P16 luff length (eye to eye) should be? I've already done all the work except attaching the head plate so would be looking at lots of unpicking to get it back to 1", but keen not to completely not stuff it up.

/Damien
klozhald

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Posted: Feb 28, 2013 - 05:13 PM

Looks like you have plenty of downhaul on that main for fair weather.
Don't worry that the main is higher- your Prindle is loose footed anyway.
You say that your problem is up top with the head plate?
Looks like you have room at the bottom to move the head plate up 1" or 2" if you need to.

If the bolt rope is a problem, unsew both ends from the sail, sew a length of same diaameter new line to one end and pull the new line inside the sail. Now sew and cut the ends of the new bolt rope.

I will be interested to see photos of this mod.

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Sheet In!
Bob
_/)_____/)_/)____/)____/)_____/)/)__________/)__
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA
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damienb

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Last visit: Aug 19, 2013

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Posted: Feb 28, 2013 - 05:33 PM

There's no real problem with the existing sail (pictured). I just want to get the luff right when cutting down the P18 sail.

Yes, the way it is now, I've cut and sewn it to be 2" longer in the luff, which will put the foot 2" lower than the one pictured. I'm wondering whether I should recut and resew it to be only 1" longer.

After I attach the head plate it's harder to go back (since the holes will have been punched).

By the sounds of it though you seem to think I'm OK with the 2" longer luff. I'll post some pics of the modification tonight.

Damien
coastrat

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Posted: Feb 28, 2013 - 07:03 PM

is that bamboo as your tller extension? i used it for the first 2 seasons on my p16 and want ot make some more for this season, it makes the BEST tiller! extremly light, floats, cheap(have like 10,000 in my backyard), and i bring several extras in case lost/stolen/broken. hope the "new" squaretop kicks azz!

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prindle 16- "BLUE RIBBON"
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damienb

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Registered: Sep 05, 2011

Last visit: Aug 19, 2013

Posts: 24
Posted: Mar 01, 2013 - 02:33 AM

No - it's aluminium, and was OK, but was broken when my crew lost their footing. I'm using PVC at the moment, which completely sx since it's too flexy (can't tack while on the wire). Going to harvest some bamboo tomorrow for my battens, and will grab a new tiller stick at the same time.

Above is my squaretop. The red section is reinforced (7 ply) while the rest is 2 ply and the arrow indicates the length of the old sail. The metal ruler indicates the batten. It's already got a bit of a batwing which is why I didn't want to move it down x 1"

The reinforced section needs manual stitching and stitching reinforcement and I need to punch holes for the head plate, which is why I wanted to check the dimensions before I finished it. Seems like the consensus is I should keep it as is. Will let you all know how it goes - thanks for the help!

/Damien
damienb

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Posted: Mar 01, 2013 - 03:42 AM

Here's a std P16 headplate (i.e., mine) for reference
The squaretop adds maybe 20% area, almost all in the top 1/3rd.

Edited by damienb on Mar 01, 2013 - 07:43 PM.
damienb

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Posted: Mar 31, 2013 - 03:35 AM

This project is now finished. The hardest part was making new tapered battens with a maple core and 500 gsm unidirectional outer. pic below

Sails well and a bit more responsive than the pin top. Get leech flutter in the very top panel, and the battens are a little too flexy in the luff. I also extended the luff too much. As you can see the there's enough tension in the bolt rope but there is no space left. I would prefer a good inch between boom and sail.

Thanks for all the advice

Damien

Edited by damienb on Mar 31, 2013 - 07:36 PM.
HULLFLYER

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Posted: Mar 31, 2013 - 06:28 AM

You could move the boom fitting on the mast 5 or 6 inches lower.
damienb

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Posted: Apr 04, 2013 - 01:48 AM

Thanks - I'd probably prefer to either tighten the bolt rope by an inch, or move the head plate down, but I can get it tight enough (just) at the moment.

I've tried this sail out now around 6 times in winds from 5-12 kts, all solo. Its a great fit for the Prindle 16. Flies a hull much easier (probably due to the moment) and responds really well to gusts. I'm sure it's not as good as a custom squaretop, but certainly more exciting than the stock sail.

Fun project in the end.

Damien
HULLFLYER

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Posted: Apr 04, 2013 - 06:27 AM

Every square top that I have had, the top batten was on an angle, Is you top batten in line with the rest of them. It is hard for me to see.
damienbThis project is now finished. The hardest part was making new tapered battens with a maple core and 500 gsm unidirectional outer. pic below

Sails well and a bit more responsive than the pin top. Get leech flutter in the very top panel, and the battens are a little too flexy in the luff. I also extended the luff too much. As you can see the there's enough tension in the bolt rope but there is no space left. I would prefer a good inch between boom and sail.

Thanks for all the advice

DamienEdited by damienb on Mar 31, 2013 - 07:36 PM.
HULLFLYER

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Posted: Apr 04, 2013 - 06:31 AM

Every square top that I have owned, the top batten was on an angle. I can not tell on your sail. May have something to do with the leech flutter.
HULLFLYER

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Posted: Apr 04, 2013 - 06:33 AM

I meant to say that the top batten was on a more severe angle.
MN3

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Posted: Apr 04, 2013 - 07:23 AM

Sail looks nice... but your sail is lacking a window, and without the boom space to see ... you have a HUGE blind spot.

I wouldn't move the boom, it will make tacking with crew much harder and may effect the booms ability to push (rotate) the mast if it is at an extreme angle

you could simply trim the bottom panel of your sail and move the clew plate up without drilling, and remounting your mast attachments
klozhald

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Posted: Apr 04, 2013 - 11:27 AM

Modify the sail to work with your hardware, not the reverse.
Remove the tack and clew plates and the batten cup, fold the bottom of the sail up to make a new batten pocket and sew it flat.
Peen the (rivets) plates and the batten cup and grommets back on and you're done.

Edited by klozhald on Apr 04, 2013 - 11:28 AM.

--
Sheet In!
Bob
_/)_____/)_/)____/)____/)_____/)/)__________/)__
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA
--
P.M.

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Posted: Apr 11, 2013 - 10:56 AM

damienb

. . . Get leech flutter in the very top panel . . . .

Thanks for all the advice

DamienEdited by damienb on Mar 31, 2013 - 07:36 PM.

Common problem=simple solution. Take a short batten (8-10"), I've used a small top jib batten or kite batten for this, and tape it to the leech half way between the sail battens. I use sail tape or 3" wide vinyl tape. Presto. So simple a cave man . . . .

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Philip
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damienb

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Posts: 24
Posted: Apr 12, 2013 - 05:39 AM

Definitely going to try that! Thanks.

Opened up a 2" slot between mainsail and boom by letting tension off and it helped not at all. When on the wire it pointed at water 2 ft away (and you look around the sails), and when on the tramp you peer under the boom anyway. Had fine situational awareness during some tricky encounters during the race on Sunday. A window is a much better solution (and less work).

Also broke all my home made battens during a very bad gybe in 20 kts. They were very good battens, but 2 days to make, 5 seconds to break. Going to make new ones with a bamboo core.

Still very happy with the sail. Fast, easier to fly a hull, and handles gusts much better.