[Rhodes22-list] Engineering Idea

[Todd Tavares]

Slim,

I think Macgregor has done something like this already. It seems like
they saw GB's mast raising system and copied it.   I didn't study your
e-mail in great detail, but are you planning to lower the mast toward the
bow? Why do all of the extra engineering when you already have a mast
crane?  Maybe you could make a two piece or folding temporary mast
crutch.  Make a single pole temporary crutch that would, say fit into a
wooden block dropped into the cockpit table socket. Or a double pole
crutch that could be spread and set down on the cockpit seats?

Set your crane up like normal.   Disconnect the furler/headstay. Connect
the crane to the foredeck and mast using the stays or a bail on the mast.
(maybe attach your spreader link thingies?)  Lower the mast unto your
temporary crutch and motor like heck under the bridge.   You may even get
away with just lowering the mast and stop it where you need it.  I do not
know how the GB crane winch works, but can't you stop where ever you want
and ahve the winch brake hold the mast?  If so, you could have your first
mate steady the mast, set the brake, and you could go aft to hold the
mast while she motors under the bridge?

You would have to do the math to see how far to lower the mast to clear
the bridge at the highest water mark.   Make the crutch to the correct
length, and find its best position/ location.

For ideas, see:  http://www.boats4sail.info/mast.html and attached
drawings.  Sorry for the crude drawings, but I didn't have a lot of time
to draw them.

Todd



----- Original Message -----
From: Slim
To: Rhodes
Subject: [Rhodes22-list] Engineering Idea
Date: Sat, 03 Sep 2005 15:30:18 -0500

>
> Lake Minnetonka, my home waters, is divided into two parts separated by
a
> bridge. If I could get under the bridge, it would more than double the
area
> in which to sail. I'm thinking of a way to drop the mast quickly to get
> under the bridge. I'm no engineer so I'm way out of my league here but
what
> about this:
>
> Eliminate the GB hoist crane and use the boom for the gin pole. Replace
the
> big GB mast crutch with a single pole. Eliminate the 8" shroud
extensions
> and replace with lever-operated quick release mechanism like some boats
have
> on running back stays and some boats have levers on the upper
> shrouds--slacking one depending on the tack.
>
> I'm imagining this procedure to take less than five minutes:
>
> 1. Slack the back stay tensioning line.
>
> 2. Disconnect the main sheet from the boom. (No need to remove the
traveler
> bar.)
>
> 3. Deploy mast crutch. (Single telescoping pole with "V" on top.)
>
> 4. Disconnect boom at gooseneck and walk the boom forward. (The two
lines
> going to the aft end of the boom, the topping lift and the main sail
> outhaul, stay connected and simply go slack when the aft end of the
boom is
> at the foot of the mast.)
>
> 5. Secure the aft end of the boom at or near the foot of the mast.
>
> 6. Disconnect bow stay and insert block and tackle between bow stay and
the
> chain plate. (The forward lowers are holding up the mast.)
>
> 7. Connect forward end of boom to the end of the bow stay/block and
tackle
> connection.
>
> 8. Throw off quick-release levers on forward lowers.
>
> 9. Lower the mast.
>
> I know the devil's in the details--how to connect the aft end of boom
to, or
> near the foot of the mast and how to connect the forward end of the
boom to
> the bow stay. The GB hoist winch won't spin if you let go of it whereas
a
> block and tackle would run if you let go. (So don't frickin' let go!)
It
> could have a cam cleat so you could set it and walk away. The boom is a
lot
> longer than the GB crane pole and would provide greater leverage but
maybe
> it's TOO long--I haven't measured--although where it hooks on to the
bow
> stay doesn't necessarily have to be at the very end of the boom.
>
> I'm just brain storming here but is this feasible?
>
> Slim
>
> __________________________________________________
> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list

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