Thickness of the gap between the double skin trans

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Thickness of the gap between the double skin trans

Post by Sabre27Admin » Wed May 10, 2017 8:22 pm

SteveV
United Kingdom
43 Posts

Posted - 11/04/2017 : 22:48:10
I am trying to work out how to get access to bolt a wind vane bracket to the transom. I am thinking of adding an inspection hatch.

Does anyone know how big the gap is between the outer and inner skin is

Castoffs
France
30 Posts

Posted - 12/04/2017 : 09:04:29 Castoffs's Homepage Edit Reply Reply with Quote View user's IP address Delete Reply
Can't remember exactly but enough for what you need to do I think. Scarab has 3 hatches, either side about 15/8cm and a circular one below all covered by air vents. They give good access to various fixings (as I found out when someone rammed our rear rail and ripped the bolts out).

Edited by - Castoffs on 12/04/2017 09:05:54

SteveV
United Kingdom
43 Posts

Posted - 12/04/2017 : 10:47:43
Thanks

The lower one on the transom in your photo is where I am thinking. Below the rubbing strafe. I just need enough access to get a spanner on the bolts. I am away from home so trying to plan things without access to the boat.

On another topic I read recently of another boat, Sabre I think, who bolted right through both layers and had to fill in between. Can't find the post now though.


SteveV
United Kingdom
43 Posts

Posted - 12/04/2017 : 11:28:43
Thanks

The lower one on the transom in your photo is where I am thinking. Below the rubbing strafe. I just need enough access to get a spanner on the bolts. I am away from home so trying to plan things without access to the boat.

On another topic I read recently of another boat, Sabre I think, who bolted right through both layers and had to fill in between. Can't find the post now though.

Castoffs
France
30 Posts

Posted - 13/04/2017 : 12:54:23 Castoffs's Homepage Edit Reply Reply with Quote View user's IP address Delete Reply
For more strength personally I would put plates on the back of the bolts inside the cavity rather than bolt right through, though others may know better.

Aesthetically I would rather have a bunged/plated hatch rather than bolts through.




SteveV
United Kingdom
43 Posts

Posted - 13/04/2017 : 13:21:31
Agreed, I plan to add plates inside the outer skin. The inspection hatch will be hidden inside what is my gas locker


SteveV
United Kingdom
43 Posts

Posted - 13/04/2017 : 14:08:54
Agreed, I plan to add plates inside the outer skin. The inspection hatch will be hidden inside what is my gas locker


Castoffs
France
30 Posts

Posted - 13/04/2017 : 14:13:08 Castoffs's Homepage Edit Reply Reply with Quote View user's IP address Delete Reply
Let us know how you get on

ken endean
United Kingdom
52 Posts

Posted - 13/04/2017 : 16:04:18
Having just seen this thread I can reply to the original query because I cut out a gate in the transom to accommodate our outboard motor and I still have the cut-out portion. The overall thickness is 40mm (below the strake)and the middle 22mm is a foam-filled void.
When Roy Tall fitted his wind vane he formed internal 'packing washers' in situ, and his method is described in Rattling Sabres No.75 (ie. the most recent edition). Note that some Sabres may not have foam filling between the two layers of GRP.
One benefit of bolting though both layers is that each side of the cockpit well then provides some longitudinal stiffness to help resist fore-and-aft forces on the windvane (or outboard motor), rather than relying completely on the flexural strength of the transom.


SteveV
United Kingdom
43 Posts

Posted - 13/04/2017 : 16:10:12
Thanks Ken

Rattling sabres is where I read about it, I couldn't remember where.

20mm isn't much to get a backing piece, plus washers and nuts.

Some time to think about it yet, I am not back until late August
Edited by - SteveV on 13/04/2017 16:15:30
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