Horizontal booms - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 04-18-2007
Junior Member
 
Join Date: Apr 2007
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
royt is on a distinguished road
Horizontal booms

Why are booms always level?


The boom on my 43' aluminium cruiser (she is about 10yrs old, I bought her last year, and am planning to start cruising next year) is high enough not to threaten the heads people standing in the cockpit, which is great. But the problem is that the base of the mast is forward of the coach roof top. This means that the deck level at that point is quite low. I have also had a batcar system fitted, but this with the low deck has resulted in the headboard being over 2metres (6-7') above the deck, managing anything that high is a problem.

I would like to move the gooseneck down by at least a meter (3'), but leave the clew height were it is. This will result in a boom that is no longer level. But I can only see advantages (lower on the mast will reduce loads on the mast caused by the gooseneck, working on the sail at any other position along the boom is also easier, lower COE on the sail, bigger sail area, longer luff). Are there any major negatives that I am not thinking of? (Horizontal airflow?)

Why do I never see booms that are not level except on open 60s?

Regards
Roy
Reply With Quote Share with Facebook
  #2  
Old 04-18-2007
Senior Member
 
Join Date: May 2006
Posts: 825
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 9
chris_gee is on a distinguished road
Maybe if you draw it out it will be clear to you.
1 you are not changing the luff length.
2 nor the sail area.
3 the air flow in the base will be less ie there is sail at the mast but none aft. At the top relatively there is none at the mast but some aft.
I don't see how batt cars move the headboard.
If you can't reach the top of the sail eg to shackle it on ( if it isn't permanent, and can't lower the whole boom temporarily then I can't see why the headboard occupies a metre. Presumably eyeheight would be over 1.7 m, so if you have a problem cut down the head board and reshape the sail.
Reply With Quote Share with Facebook
  #3  
Old 04-18-2007
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 9 Times in 9 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Actually, if you're not getting the sail recut, you are going to cause a problem. By lowering the boom, you effectively shorten it, unless you have a non-loose-footed main, in which case, you'd have to recut the sail to do this anyway. This means the sail will be fuller under most conditions, and that can cause you some serious problems when the winds are very strong, since it will be difficult to depower the main. Also, unless you use a pennant at the tack, the sail won't be able to be hoisted fully. It'll be a meter short of full hoist. If the sail isn't re-cut, and you're not using a tack pennant, then the sail will be lower by a meter for its entire length—since the sail is what supports the aft end of the boom.

Also, reefing the sail will be a problem. If the sail reefs using tack hooks, on the boom, you're going to have a problem because if you do use the tack hooks the new, reefed clew is going to be higher than the reefed tack, and the leech of the sail will bag.

Personally, IMHO, you're asking for trouble. Why not just install a few mast steps, and use them when you have to work on the boom or headboard of the lowered mainsail. It is probably far less trouble and definitely going to cause far fewer problems.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Share with Facebook
  #4  
Old 04-18-2007
Senior Member
 
Join Date: Jun 2005
Posts: 135
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
Hawkeye25 is on a distinguished road
One other little item - the vang. If you have a vang rigged, lowering the gooseneck 50% may result in actually tripling the loading on the vang, possibly resulting in an explosive failure, maybe even having the lower mast fitting coming at the cockpit approaching the sound barrier, though it would probably only fail if the boom was well overboard. Put a folding step and a handhold on the mast and simply step up to fuss with the headboard. It's not perfect, but it helps.
Reply With Quote Share with Facebook
  #5  
Old 04-19-2007
Junior Member
 
Join Date: Apr 2007
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
royt is on a distinguished road
Thanks for the responses.

Something I didnt mention was that I need a new main as well, so it would be cut to suit the new boom angle. Including putting in the reefing points to suit the boom angle.

To explain how the batcars raise the headboard.

The boom is perhaps 5' off the deck, the combined length of the batcar sliders and headboard when the main is lowered is perhaps another 3', resulting in the headboard being at least 8' off the deck. I agree that you could get at this with a few mast steps, but it certainly doesnt feel like a safe option for a cruising couple who may/will be caught out in poor weather.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Windlass - Horizontal or Vertical? PBzeer Gear & Maintenance 8 03-03-2006 05:51 AM
Masts and booms CHEAP trecksail Gear & Maintenance 0 02-06-2005 09:15 PM
Deadly Serious about Booms John Rousmaniere Seamanship Articles 0 10-12-2004 08:00 PM
Need wood mast and 2 booms bill4991 Gear & Maintenance 2 06-05-2002 07:20 PM
Preventers on Wishbone Booms Mark Matthews Gear and Maintenance Articles 0 05-15-2002 08:00 PM


All times are GMT -4. The time now is 04:54 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.