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Old 17-05-2018, 23:41   #1
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A new design boom cover - am I missing something ?

A wider lower profile boom bag. Can anyone think of a reason why not ?

My boat gets pushed around more than most in the wind at the marina and I'm up for a new boom bag. I thought I can fix two problems with one solution and save some money while I'm at it.

If I make a hard lightweight platform on top of the boom to form a wider bed for the sail to lie on when not in use I can halve or more the surface area to the wind of the bag.

Other side effects/benefits :-
  • the lazy Jacks will be wider apart
  • the cover can just be press studded to the bed and wrapped around the sail. Then the cover completely removed when sailing to improve air flow
  • The cover can be just a 2D piece of fabric with press studs fitted - cheap
  • the sail bed would be formed to act as a winglet to the main and reduce pressure losses from under the sail (no reefs only)
I can only see benefits but there must be some reason all booms aren't made this way ?
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Old 17-05-2018, 23:45   #2
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Re: A new design boom cover - am I missing something ?

very interesting. I like the idea also. Trying to get my mind around how to reef it though.
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Old 18-05-2018, 02:55   #3
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Re: A new design boom cover - am I missing something ?

Like these?

http://ballengerspars.com/photos/Wylie48boom%281%29.JPG
http://www.offshorespars.com/booms/park-avenue-booms/
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Old 18-05-2018, 05:53   #4
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Re: A new design boom cover - am I missing something ?

Yes just like them, I imagined something a bit wider but that may not be possible.

The rail would loose the winglet effect which I think would be measurable so I'll stick with the solid section.

I'll have a good look at it tomorrow.
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Old 18-05-2018, 06:56   #5
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Re: A new design boom cover - am I missing something ?

Over the last several years, we've looked at getting a boom rack or antlers made for our J130 Hall Spar we have on our boat. (and yes we have a more modern racing spar on our old style boat). We have looked at lots of designs during this time.

The carbon fiber Park Ave./V-boom are very nice with the integrated tracks to minimize the cover. These would be the best design to fit your idea/meet your goals, but they are very expensive.

With the rack, the cover to encompass it will become much bigger, creating more windage and the opposite of your final goal. Tracks would need to be integrated on the boom or on the rack to reduce the cover surface area.

Another boom with an integrated low profile cover would be a Leisure Furl/Scheafer in boom furler. There would be no need for lazy jacks and everything is integrated. Not my cup of tea, but many like them.

Would like to a see what you come up with for a design of a solid "rack" to attach to an aluminum boom. Since it's not structural, solid wings could be made out of carbon fiber and then riveted on the boom. It would then be fairly easy to attach a track to the top edge of the wing. The cover on the Leisure Furl was slick with a continuous line.



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Old 18-05-2018, 10:29   #6
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Re: A new design boom cover - am I missing something ?

I built an 80' cutter at Palmer Johnson years ago. I had a full batten main with Harken cars. It was quite a big main and just myself and my wife to deal with it so I had a wide boom (like Endeavor) designed and built for it. As I recall it was about 18 inches wide and flat on top so I could walk down it and flake the main, and to put the cover on. It worked really well and also provided a nice place to sit over the water when reaching, and great a great place to take photos of the boat when underway. If I were to do it again though I would dish it deeply with drains so that the sail could lay in the depression, because when I brought the lazy jacks forward to hoist, the sail would occasionally slide off the shelf.

I was very happy with it, i put handrails on the sides to grab onto. Only con was that it was heavy.

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Old 18-05-2018, 11:14   #7
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Re: A new design boom cover - am I missing something ?

Mikem,
Would love to see pics of that boom if you have them.

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Old 18-05-2018, 11:57   #8
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Re: A new design boom cover - am I missing something ?

like this?
ROAM's Rig — Sail Surf ROAM
ROAM's Rigged — Sail Surf ROAM

if so then he discusses the building of it and where he got the design from on a forum somewhere,i just can't find it at the moment although he's pretty good at answering questions if you want to discuss it with him
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Old 18-05-2018, 14:05   #9
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Re: A new design boom cover - am I missing something ?

A lot of Chamberlin catamarans have the end plate boom. It is a great idea and really good for those who have built their own boats. You can make them up the same way you built the rest of the boat. A friend built one for his Schionning 48 and it works really well. Not much to it but they do seem to have max width about 30% aft and taper back from there. Built from foam and glass.

Look at the video of Big Wave Rider and you could ask Chamberlin designs for plans, or just make it from 12-15mm foam and 600 biax with a reinforcing rim around the edge and up the centreline . (Guessing there).



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Old 18-05-2018, 14:58   #10
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Re: A new design boom cover - am I missing something ?

If I understand this correctly, Dave wants to reduce his in slip windage by having a wider opening for the sail to come down into.

I think he could do this with "antlers" like Jon Mc Conaghy has on Second Time Around. It is a relatively light weight solution, easy to work with and does not require a complicated mainsail cover. The "antlers" are s/s bar stock, that are removable, they just put them in their sockets on the boom before they drop the sail. Sorry, no pics.

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Old 18-05-2018, 16:25   #11
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Re: A new design boom cover - am I missing something ?

One of these days I'm going to get off my butt and make one of these. The plan is to make a strip plank canoe shaped boom out of cedar. Laminate with epoxy fibreglass cloth and carbon fibre. The ends open and a plastic square section tube glassed in on the bottom to handle the reefing lines. Lazy jack lines to the gunwales. Maximum beam near the mast where the bulk of the sail lands.
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Old 18-05-2018, 18:07   #12
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Re: A new design boom cover - am I missing something ?

Quote:
Originally Posted by Bill O View Post
Mikem,
Would love to see pics of that boom if you have them.

Bill O.
I will have a look, will have to scan it because it was pre digital cameras.. 1990... doesn't seem that long ago... Here is the only digital photo I have...
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Old 18-05-2018, 20:26   #13
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Re: A new design boom cover - am I missing something ?

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Originally Posted by captmikem View Post
I will have a look, will have to scan it because it was pre digital cameras.. 1990... doesn't seem that long ago... Here is the only digital photo I have...
Mike, that photo sure brings back memories! We might well have photos from either Tonga or Fiji, but they too are film and in albums back in the USA, so no hope of retrieval!

Turmoil was (is, I suppose) a gorgeous boat!

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Old 18-05-2018, 21:30   #14
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Re: A new design boom cover - am I missing something ?

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Mike, that photo sure brings back memories! We might well have photos from either Tonga or Fiji, but they too are film and in albums back in the USA, so no hope of retrieval!

Turmoil was (is, I suppose) a gorgeous boat!

Jim
Thanks Jim, I really enjoyed building and then sailing her, German Frers is a real wizard.

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Old 19-05-2018, 05:35   #15
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Re: A new design boom cover - am I missing something ?

I had a measure up today and it doesn't look to be a problem. Reef lines will be fine. Only issue I have is the mains track cars are 1200mm (4') tall up the mast when stacked so the mast end (insert technical old salty name for it here) of the sail will ramp up the mast quickly and might look a bit odd.

I'll draw it up tomorrow and post it for comments.
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