Centaur beefing up keel area

[Lodds]

I plan to beef up-up the keel area by spanning it with 18mm ply covered by 600gm triaxial cloth and using epoxy resin. My question is "How much cloth to use"
Does anyone have any knowledge on this subject. Obviously the intention is to make the span an integral part of the hull. But how much cloth to use to do that?

Tony

 

[[70521]]

Have you contacted the Westerly Association?

 

[Jcorstorphine]

I would use three.

I plan to beef up-up the keel area by spanning it with 18mm ply covered by 600gm triaxial cloth and using epoxy resin. My question is "How much cloth to use"
Does anyone have any knowledge on this subject. Obviously the intention is to make the span an integral part of the hull. But how much cloth to use to do that?

Tony

Job is similar to putting in stiffening at engine beds in the hull, I have used three layers in the past with the 1st and 3rd layer being chopped matt with the second layer being woven roven. I only used polyester resin but then that was in new hulls.

I may be wrong but I am not sure it justifies the use of Epoxy but I have never used it so best to take heed of what others may say.

 

[VicS]

I plan to beef up-up the keel area by spanning it with 18mm ply covered by 600gm triaxial cloth and using epoxy resin. My question is "How much cloth to use"
Does anyone have any knowledge on this subject. Obviously the intention is to make the span an integral part of the hull. But how much cloth to use to do that?

Tony

There is a fair bit of info on the Westerly owners association Yahoo Discussion group You have to register with Yahoo to access it but you do not have to be member of the WOA. ( I use SWMBO's old Yahoo email identity)

There are a number of diagrams and photos in the "photos" section showing how to beef of the hull around the keel area Posted way back in 2006 so you have to click through to the relevant page
Maybe this will take you there direct http://groups.yahoo.com/group/Westerly-Owners/photos/album/1237689016/pic/list


Also worth looking at the WOA forum. Again you do not have to be a member of the WOA.

 

[Lodds]

There is a fair bit of info on the Westerly owners association Yahoo Discussion group You have to register with Yahoo to access it but you do not have to be member of the WOA. ( I use SWMBO's old Yahoo email identity)

Yes I am a member but cannot find the information I need regarding how much cloth to use.

Thanks

 

[Jcorstorphine]

Here are some links

I plan to beef up-up the keel area by spanning it with 18mm ply covered by 600gm triaxial cloth and using epoxy resin. My question is "How much cloth to use"
Does anyone have any knowledge on this subject. Obviously the intention is to make the span an integral part of the hull. But how much cloth to use to do that?

Tony

Have a look at these links.

http://www.ybw.com/forums/showthread.php?t=75166

http://www.ybw.com/forums/showthread.php?t=226074

They do not answer your question in terms of how many layers but there are several points of view in terms of method etc. However I do stand by my suggestion of three layers and I would overlap each previous layer by a 25 mm.

Some say that you should lay one layer on top of the other with little or no time interval in-between successive layers. Danger of this is that the laminate will get hot (well polyester does) and the last layer may cure before it is rolled out. Not sure how Epoxy will react but I would try a test laminate using say a layup of 3 x 100 mm square bits of cloth.

One other point, have you used triaxial cloth before in something like the confined cross section of the internal keel stub? I have no experience of Triaxial but have found woven roven tricky to conform to compound type curve (but perhaps that is why you are using triaxial)

Last point is (and forgive if I am trying to teach my granny to suck eggs) don’t be tempted to use one piece and lay it over the edge of the 18 mm ply as I am sure it will spring off. Start with a small filler strip just to locate the plywood in the keel stub, perhaps only a having a 50 mm wide strip so that you can concentrate on getting good contact to the ply and the hull.

Very best of luck


PS quite a bit of info here about laminating stiffners in GRP hulls.

http://www.google.co.uk/#hl=en&suge...58,d.Yms&fp=1b06cd1115cee478&biw=1024&bih=633

 

[GrahamM376]

I plan to beef up-up the keel area by spanning it with 18mm ply covered by 600gm triaxial cloth and using epoxy resin. My question is "How much cloth to use"
Does anyone have any knowledge on this subject. Obviously the intention is to make the span an integral part of the hull. But how much cloth to use to do that? Tony

I've done this on a Centaur and a Berwick, using standard polyester with chopped strand mat with a couple of layers of woven. In both cases, the areas were first dried with fan heaters for several days and cleaned off with large grit abrasive flapper wheels then acetone. Many years later, they're both still OK with no delamination.

When the keels stubs fail, the entire bottom can fall out the exact shape of the keel so, the entire keel stubs need covering with several layers to maybe 3-4mm thick, well rollered, and also up the hull/into the bilge some distance with decreasing thickness. The ply bulkheads can be glassed in after a few layers are laid up in the stubs.

Unfortunately can't remember the quantity used but it was several meters of mainly medium grade chopped strand mat.

 

[Lodds]

When the keels stubs fail, the entire bottom can fall out the exact shape of the keel so, the entire keel stubs need covering with several layers to maybe 3-4mm thick, well rollered, and also up the hull/into the bilge some distance with decreasing thickness. The ply bulkheads can be glassed in after a few layers are laid up in the stubs.

While this was happening had you dropped the keels first? My plan is to undo maybe up to two nuts at a time cover the thread with insulation tape and glass around the base of the thread and as you suggest up the bilge/hull.
Epoxy is unlike polyester in that the curing time is based on ambient temperature only, so the amount of hardener you use remains static. I'm no expert either but I understand that two or three layers at a time will be okay, and yes it gets very hot. Point noted thank you.

 

[GrahamM376]

While this was happening had you dropped the keels first? My plan is to undo maybe up to two nuts at a time cover the thread with insulation tape and glass around the base of the thread and as you suggest up the bilge/hull.

The Centaur keels had already been re-bedded, that's when the stress cracks were found, not too bad, so we did as you suggest. Bear in mind that with splayed keels, there's a tendency for them to move as the load varies so we lowered the hull onto blocks to take the boat weight and wedged the keels to stop any movement.

With the Berwick we also re-bedded the keels at the same time so similar setup but higher, so keels could be dropped far enough (on a trolley jack and a couple of scissors) to scrape the joints and apply new sealant. As I was intending selling the boat soon after, I had a surveyor (Mark McGarry) inspect the work in stages and certify the job.