boom.

General chat about boats
Michael Brigg
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Re: boom.

Post by Michael Brigg » Sun Jun 24, 2012 12:20 pm

I seem to recall someone on this forum showing us how to convert a L***r cockpit into Mud guards on their road trailer. :twisted:

So at risk of being an off topic forum "Gravedigger!" :) ...

viewtopic.php?f=4&t=1424


And recently we have heard from Trebor, about how little use the laser cockpit is for anything else. :evil:

...So we have established that a good use of a l***r is for cannibalism

download/file.php?id=37

download/file.php?id=38
Michael Brigg

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jpa_wfsc
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Re: boom.

Post by jpa_wfsc » Sun Jun 24, 2012 4:23 pm

trebor wrote:the teardrop alloy tubing used on light weight push bikes would be ideal then, very strong and light also only about 1mm thick.
Not as strong as you think - they often crack near the bottom bracket, and they are only stiff because they are only 2 to 3 foot long and are welded in to a triangle frame. If you had an 8 foot boom made from that section it would be as bendy as a topper boom. Crome-Moloy frames are far far stiffer, despite being half the diameter, without being heavier, but are also far more expensive.
j./

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!!!! Not CVRDA !!!!
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trebor
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Re: boom.

Post by trebor » Sun Jun 24, 2012 9:45 pm

Hi fcbdm, the problem with boom on Aquabat is that it is over 10 feet long, most split mast sections are probably shorter.
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
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Rupert
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Re: boom.

Post by Rupert » Mon Jun 25, 2012 8:43 am

My Minisail boom is cut from a Solo mast which I was given, so if you are lucky, there are free or cheap unbent masts out there.

Also, a longish mast bent at deck level would still have enough straight before the taper starts.

Also (again) I wonder if an old Ali Mirror mast might work? Must be about 11 feet long.
Rupert

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Nessa
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Re: boom.

Post by Nessa » Mon Jun 25, 2012 9:42 am

I have the remains of the kestrel mast, easily 10 foot, but how long it would stay in shape I can't be sure. It probably has too many holes from fittings, spreaders etc to be of any use.

Oh, and this weekend a sailor needed sixteen stitches after a clash with a challenger boom. We still haven't worked out how he got his head up that high. :cry:
The Peril
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trebor
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Re: boom.

Post by trebor » Mon Jun 25, 2012 5:57 pm

Hi nessa, thanks for consideration regarding old mast, I intend to change from aft/centre main to a true centre main, getting rid of loads of main sheet, I tend to get slack stuck on various bits of the boat, on the Laser I was getting the sheet stuck on the corners, I know some of the problem is due to lack of experience, but if the mainsheet is all in centre of boat their are less objects to snag, hence I will need a decent length of tube.
a work colleague was picked out of his dinghy by a boom on another boat, the end of the boom went under the shoulder strap on his bouyancy aid, during the melee to make a rounding.
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

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Nessa
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Re: boom.

Post by Nessa » Mon Jun 25, 2012 6:33 pm

be careful - an aft main does a lot of work towards controlling the leech, especially on older designs. I converted the Bonito to centre main, then chaged it to the laser style arrangement just to get that leech control,back.
The Peril
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trebor
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Re: boom.

Post by trebor » Mon Jun 25, 2012 7:49 pm

Hi Nessa, I am not quite clear on how centre/aft main can have an effect on leech, I had assumed it was purely to move boom from one tack to another, purely power control.
Robert
Minisprint 4230
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Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

SoggyBadger
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Re: boom.

Post by SoggyBadger » Mon Jun 25, 2012 8:19 pm

trebor wrote:Hi Nessa, I am not quite clear on how centre/aft main can have an effect on leech, I had assumed it was purely to move boom from one tack to another, purely power control.
The lack of leech control comes from the boom bending with centre main although for a boat like yours it probably won't matter.
Best wishes


SB

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trebor
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Re: boom.

Post by trebor » Mon Jun 25, 2012 9:03 pm

Hi Paul, I intend to fit a new boom that will not bend, the one that is on is about the same diameter as a broom stale and while adequate for original spec( Beach boat, aft rigged, simple downhaul and outhaul ) and for rigging as is now centre/aft main, it would bend like a bow if you tried a full centre main, I have at the moment a 12 foot length of 50mm alloy tubing ( new ), I will use this if necessary but if their is a better profile or if a bigger diameter tube would be better I will use that.
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

fcdbm
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Re: boom.

Post by fcdbm » Mon Jun 25, 2012 10:07 pm

Broken Laser topmast measures 3270mm from tip to break.

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trebor
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Re: boom.

Post by trebor » Mon Jun 25, 2012 10:11 pm

Hi fbcdm, that would be plenty, what diameter is it?
Robert
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Rupert
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Re: boom.

Post by Rupert » Tue Jun 26, 2012 8:34 am

A Laser top mast would bend too much for a centre main - If I remember right, the Laser boom is a sleeved version of the same tube, and that still bends like a banana.
Rupert

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trebor
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Re: boom.

Post by trebor » Tue Jun 26, 2012 7:05 pm

Hi Rupert, with true centre main and kicker very close together, more than half the boom is going to have to control leech so has you say it is going to need to be very stiff.
Nessa, I see what you mean about centre/aft main helping with leech control, I intend to fit a much stiffer boom though.
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

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