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Planning the F14- Step 1-b: Mainsail design #31676
03/21/04 09:12 PM
03/21/04 09:12 PM
Joined: Apr 2002
Posts: 591
Bradenton, FL
Sycho15 Offline OP
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Sycho15  Offline OP
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Joined: Apr 2002
Posts: 591
Bradenton, FL
I want to start getting some prices from various lofts on the cost of sails- especially the mainsail, as this will be the most similar sail on every boat.

First- Boom or Boomless? Most racing boats go with booms for the added tuning ability. The Mysteres are running boomless and don't seem to mind at all. I personally prefer a boomless sail, with a stiff lower batten and an inhaul from the tack to the clew to adjust the flatness/fullness of the sail.

Second (because it is dependant on the condition above)-with a 24' mast, how long can the luff of the sail be?

Third- how long should the foot of the sail be? Mostly, this depends on the location of the mast beam- but with a boom, the sail could extend past the aft beam.


G-Cat 5.7M #583 (sail # currently 100) in Bradenton, FL Hobie 14T
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Re: Planning the F14- Step 1-b: Mainsail design [Re: Sycho15] #31677
03/24/04 09:26 AM
03/24/04 09:26 AM
Joined: Jun 2001
Posts: 778
Houston
carlbohannon Offline
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carlbohannon  Offline
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Posts: 778
Houston
First, after trying both systems, I am going with a boom. It gives much better sail control and reduces sheeting loads.

The big advantage of a boomless boat is it sets itself going upwind but it is never sets itself quite right. Also, booms are expensive figure $500 retail or $150 if you build it yourself.

For foot lenght, the practical limit is about a foot aft of the traveler.

For efficency the foot of the sail angles upward (~30 deg). With long booms you get into diminishing returns plus it starts looking a little odd

As you sheet ou the CF moves aft. The CF runs from ~1/3 - 3/4 the boom lenght from the mast. Don't let the CF get too close to the rudder. I have only sailed one boat whose boom extended significantly past the rudders and as the owner warned me "don't sheet out too much in a puff, it gets strange"

Long booms are just awkward.

Who's got the longest... boom. [Re: carlbohannon] #31678
03/24/04 09:44 AM
03/24/04 09:44 AM
Joined: Jun 2001
Posts: 3,279
Long Beach, California
John Williams Offline
Carpal Tunnel
John Williams  Offline
Carpal Tunnel
Joined: Jun 2001
Posts: 3,279
Long Beach, California
Take a look at this shot from a race here in P'cola last month. I was amazed how long the boom is on Bob's creation - for comparison, look at Sue Korz's 16 in the background... both appear to extend aft past the rudders...

Attached Files
31755-h14boom.jpg (614 downloads)

John Williams

- The harder you practice, the luckier you get -
Gary Player, pro golfer

After watching Lionel Messi play, I realize I need to sail harder.
conversely... boom [Re: John Williams] #31679
03/24/04 09:59 AM
03/24/04 09:59 AM
Joined: Jun 2001
Posts: 3,279
Long Beach, California
John Williams Offline
Carpal Tunnel
John Williams  Offline
Carpal Tunnel
Joined: Jun 2001
Posts: 3,279
Long Beach, California
here's a shot of Rod Waterhouse in the same race - notice the Nacra 20's boom is barely aft of the traveler, but the sail is well inside even that. Hobie 14/16 = long boom aft of traveler, Nacra = shorter boom, even shorter foot... I suppose there is some physics in there relating to hull shape and some other stuff too, eh?

Attached Files
31756-i20boom.jpg (557 downloads)

John Williams

- The harder you practice, the luckier you get -
Gary Player, pro golfer

After watching Lionel Messi play, I realize I need to sail harder.
Re: conversely... boom [Re: John Williams] #31680
03/24/04 12:21 PM
03/24/04 12:21 PM
Joined: Apr 2002
Posts: 591
Bradenton, FL
Sycho15 Offline OP
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Sycho15  Offline OP
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Bradenton, FL
OK, I can settle with a boom. I think H14 booms would be fine to use, as you don't have to have a sail that slides inside the boom along it's foot.

What else, besides old H14 mast sections, would make good booms? Surely there is a cheap way to cobble together an effective piece of equipment.



G-Cat 5.7M #583 (sail # currently 100) in Bradenton, FL Hobie 14T
Re: conversely... boom [Re: Sycho15] #31681
03/24/04 01:25 PM
03/24/04 01:25 PM
Joined: Mar 2002
Posts: 284
Norfolk, VA
Dan Berger Offline
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Dan Berger  Offline
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Posts: 284
Norfolk, VA
I wouldn't use a mast section, that would be way too big. A regular H14 or H16 boom would be easy to find and should work. If you are looking for a stock extrusion, the H17 boom is nice and small. They are pretty hard to find used, though.

If you look at the A-cats, they have a really small aluminum, fiberglass or carbon boom. The blocks attach where the leech attaches to the boom, so the boom is really only there to hold the sail out where it should be and to give you some foot adjustment. They also have a semi-circular or elliptical traveler, so the force is always pretty much straight up and down compared to the angle you get on boats like the 14 and 16.

The Hobie 14 Mylar square top sail I ordered from Sabre came loose footed. I expected it to be footed like Bob's, but it wasn't and I'm pretty happy with it. I can get a really nice shape out if it after a little boom modification. I took the outhaul adjustment from a Prindle 16 and installed it on the 14 boom. Works great and is easy to adjust. Just another idea.


Dan Berger
Norfolk, VA
A Cat USA139
Supercat 15
Re: conversely... boom [Re: Sycho15] #31682
03/24/04 09:41 PM
03/24/04 09:41 PM
Joined: Apr 2002
Posts: 170
Australia (Queensland)
Berthos Offline
member
Berthos  Offline
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Joined: Apr 2002
Posts: 170
Australia (Queensland)
Quote
OK, I can settle with a boom. I think H14 booms would be fine to use, as you don't have to have a sail that slides inside the boom along it's foot.

What else, besides old H14 mast sections, would make good booms? Surely there is a cheap way to cobble together an effective piece of equipment.



The boom on a Taipan is simply some aluminium tube with fittings attached. These are lightweight and would be very easy to make at home. There is very little load on a Taipan boom as the mainsheet blocks are attached to the clew of the sail rather than the boom. The boom is used to adjust the location of the clew so the only loads are basically compression. There are blocks and a cleat attached to the boom to enable outhaul adjustment and a sort of universal joint where the boom attaches to the mast. The sail is loose footed of course. Depending on the set-up there is also attachments to the boom for over-rotation control.

The first photo below shows the rotation control and the 'universal joint'. The universal joint is simply an aluminium block with two holes in at right angles to each other and at opposite ends of the block. A bolt runs through the boom and through the block at one end and the other end of the aluminium block is attached to a bracket on the mast with a pin. The block is able to move up and down within the boom. There may be some spacers and bushes inside the boom - I've never looked.

The second photo shows the outhaul. There is a pulley attached to the clew which is a little difficult to see in the photo. This setup gives a 3:1 purchase on the outhaul. The outhaul line goes through the inside of the boom and exits about halfway along where there is a cleat. Not shown in either photo.

I hope this is of some assistance.

Rob.

Photos courtesy of F16 website: http://www.geocities.com/F16HPclass/

[Linked Image]

[Linked Image]

Re: conversely... boom [Re: Berthos] #31683
03/25/04 09:07 AM
03/25/04 09:07 AM
Joined: Apr 2002
Posts: 591
Bradenton, FL
Sycho15 Offline OP
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Sycho15  Offline OP
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Joined: Apr 2002
Posts: 591
Bradenton, FL
I'm afriad the photos didn't work, but the description was very precise. I think I could build one from your description and my imagination- thanks a ton


G-Cat 5.7M #583 (sail # currently 100) in Bradenton, FL Hobie 14T
Re: conversely... boom [Re: Sycho15] #31684
03/25/04 09:17 AM
03/25/04 09:17 AM
Joined: Jun 2001
Posts: 885
Dunedin Causeway, FL
David Parker Offline
old hand
David Parker  Offline
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Joined: Jun 2001
Posts: 885
Dunedin Causeway, FL
The photos come up if you wait a bit. However, the complete link to the page with those photos is

Taipan 4.9 Rigging Info


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