Raising & lowering the mast

The prime movers for your Cape Cutter 19.....

Re: Raising & lowering the mast

Postby oak » Wed Nov 28, 2018 4:50 pm

Hello all,
I have read all the above but still am a little uneasy of side movement of the mast in wind or popple. .
I really like the A frame approach
http://www.shrimperowners.org/sitefiles ... lifter.pdf.

this seems rather good.
They take the purchase to the bowsprit,would it make a lot of difference fastening off where the CC forestay attaches.
Could the genoa halyard go through the ring into the purchase and back to the winch.
I used to just use the genoa halyard though a block on a raised bowsprit but don't like the risk of sideways movement wrecking the deck.new mast is much heavier anyway.
One downside is the cost of 4 spinnaker pole fittings.Any ideas on cheaper alternatives.
waiting for the expert replies
Merlin
Jack
oak
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Re: Raising & lowering the mast

Postby Malcolm Sadler » Mon Dec 10, 2018 6:51 pm

To continue this discussion....

Thanks to Jack for the link to how a shrimper has done it.

It seems to me only a partial solution however, and only lends triangulation for the first half of the raising of the mast - which from one point of view is the least risky stage as the mast is then lowest and least affected by the putative cross wind or roll. For the second half of the raise, the Gamba's skipper has cast aside his two spars and is in the same state as those of us who have no A frame - and this is when the mast is high in the wind / the effect of a roll is greatest as the centre of gravity is highest.

For such a partial solution I personally would not do all Gamba's engineering, but would prefer Dennis's much simpler "guy rope" solution, which I recall clips guys to the bowsprit shroud fixings on the gunwales. Dennis may have posted photos - and my apologies Dennis if I am mis-remembering what you showed me in Largs.

For real security, don't we want to stop the mast swaying sideways, not just the the raising pole or line that is attached to the masthead? If we had no tabernacle, so the fulcrum for the mast were at coach roof level, we could put port and starboard eyes in the coachroof near the gunwales in line with the mast foot and create a rigid A frame, with spars a la Gamba but connecting to the mast itself. That would be the ideal as the mast would be triangulated.

But we do have a tabernacle,so the fulcrum is about 18" above coachroof level and more above gunwale level. In the absence of skyhooks, we would need:-
(a) a bit of clever engineering to raise (to tablernacle height) the spar-anchoring eyes on some sort of parallelogram frame each side
or
(b) leave the the eyes at gunwale level (ie. use the existing bowsprit shroud eyes) and attach the tops of the two spars to a ring which would slide up and down the mast as it is raised.

I confess, this last proposal has only occurred to me as I type this post, but at first sight it may be a reasonable solution. Rings/hoops - leather covered or with parrel beads - sliding up and down gaff rig masts are a long proven technology, and we just need one which opens on a hinge, with two small diameter S/S rings welded on the outside into which the tops of the two spars will clip.

I realise I have now proposed a system with three long bits of wood:-
- I still need my raising pole, which would be still be subject to swaying in the wind or rolling sea but with much less risk as the mast is secure and will tend to keep the pole upright rather than to pull it out of the vertical. If the mast is certain not to move sideways I would be willing to use my bowsprit for this (as the risk of damage to it from sideways force is eliminated).
- I then need two spars for my A frame, but these only take longitudinal compression force - no bending, so they can be thin and light.

I'll leave the idea there. As I say, it's just occurred to me and is offered in its raw state. I expect the engineers and sea salts among you to respond with comments on why it is flawed, but if we don't brainstorm a bit we don't innovate!

All the best

Malcolm
Malcolm Sadler
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Re: Raising & lowering the mast

Postby oak » Sat Jan 26, 2019 12:44 am

Malcolm,
I have replied,no not accurate,have tried twice to reply but both times message zoomed off to the ether.I was trying also to put a picture up.
I think I am going to try the twin pole method as I think there will be enough lateral stability in order for me to raise the mast to a point that I will be able to support it and push it into the tabernacle.I will be standing on the coachroof just behind the mast.
The stumbling block at the moment is the cost of 4 spinnaker pole ends.Perhaps you can suggest alternative ways of clipping the wood poles to deck and mast ring.
Jack
oak
CC19 Association Member
 
Posts: 129
Joined: Mon Apr 06, 2009 9:15 pm
Location: ireland

Re: Raising & lowering the mast

Postby Malcolm Sadler » Wed Jan 30, 2019 1:26 am

Hello Jack.

Thanks for persevering with your lost post - and it’s good to know that there is still a spirit of experimentation out there.

I’m afraid I have no magic solution for spinnaker pole clip replacements. Sorry

I see there are two complete dinghy poles on eBay currently at £20 each. I imagine they come up from time to time and that or a boat jumble may be the sort of places to look.

Do keep us posted as the design progresses.

All the best

Malcolm
Malcolm Sadler
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Posts: 97
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Re: Raising & lowering the mast

Postby oak » Thu Jan 31, 2019 10:52 pm

Hello Malcolm,
thanks for the ebay tip.I have got it into my head that I want to use wooden poles.Spinnaker fittings for aluminium poles are cheap enough but difficult if not impossible to use on wood.I am not a Major Tilman ,I tend to get rather worried if everything is just not so .
Jack
oak
CC19 Association Member
 
Posts: 129
Joined: Mon Apr 06, 2009 9:15 pm
Location: ireland

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