600 GSM Biaxial Fiberglass

Never used it before and I am looking for some tips.

This is the plan.

Building harddecks for a Seawind 24. Using 15mm Polycore and a layer of 600 gsm Biaxial each side. I plan to take a 45 degree bevel around the polycore and set it back some 25mm to 35mm from the finished edge/size. Glass the bottom of the core taking the glass over the bevel and down onto the same plane as the top of the core + the 25mm to 35mm. In reality it will be more than that and I will cut back to the desired shape. Then I will glass the top of the core over onto the edge/ ledge created when doing the bottom of the core.

This serves a few purpose's...

1. It seals the core.
2. It gives a thin edge which can slide into the slide track on the main beam (it is a mast section).
3. It gives a solid edge which can be fastened onto some newly fashion mounts. The old tramp rails are going west...

I realise that the glass will not stick to the naked core across the 45 degree bevel but I don't see that as a major issue, also the exposed core will tend to fill with resin, I intend to take some measure to prevent/minimise this.

The main question is... I believe that two layers of 600 gsm will not be enough around the edges so I expect to have to reinforce about a 50mm wide strip around the edge. I want to end up with around 6mm of solid glass around the edge, that's a wet finger in the air guess but I think that will work well. How many layers of 600gms should I allow for to do this.

Wordy for a simple question I know but I thought maybe the extra info will bring forth some other advice.

Thanks in advance.

MBz

Edit: I'm using polyester resin....

Edit: I just read a Duracore document that says 0.53mm per layer of 600gsm. Sound correct?

 

Vacuum bagging might produce that 0,53mm. Hand layup some more especially if you don't do wet on wet. So I'd say 0,7mm/layer in this case. However I'm just quessing now and got to take some sampes to measure/confirm that..

 

Have a yac with Fanie...

 

Another way

Hello Meanz

I am about to go the polycore way for my bag cats new top. However I think that I will treat it pretty similarly to Duflex or Featherlight.

To treat the edges in Duflex or Featherlight (more like Polycore) for this type of thing - like a cupboard cutout - you cut away the core with a router or sharp knife, whichever way you find best for you - I like a screwdriver and lots of energy. You remove it to a depth of about 10mm. Don't be cute about it - just get rid of core. Then you fill the void with epoxy filler. Fill right up to the top of the leftover skins.

After this I would then round off the edges to allow the glass to sit well on the core. A 15mm diameter round is tight for 600DB. It may work but if not use normal glass cloth - yeah cloth and cut it strangely.

For tight corners my favourite trick is to cut normal tight weave cloth at 45 degrees to the roll so that you make your own tight weave DB. About 3 layers of 10oz will be more than enough.

My advice is not to do 6 mm of glassing - that is over the top in my opinion. I also wouldn't bother with vacuum bagging. VB does a great job of making edges stick but you can lose control of the part when it is in the bag. It is pretty expensive and wasteful. I did huge amounts of it for a trimaran project and could bag almost anything but don't do it now.

If you can almost get the 600DB to stick but it just won't lie down use a bagging trick and peel ply the edges with lots of peel ply onto the panel itself.

cheers

Phil

 

Another read

A quick re-read has me reserving my initial position

I don't like the idea of inserting a composite panel into a mast track. I can see real problems with chafe and hard points. Composite panels work by spreading loads, not be concentrating them.

I would mould off the beam (or something like it) and have a large flange for the mast beam part. At the sides you could make a flange that sits up or down for bolting to the boat. Better still glue and glass a piece of wood or PVC onto the hulls and mount the floor on top.

Use boat parts to mould to and have large flanges that spread loads. You may be able to mould off the main beam in one morning with some wax and polyester.

cheers

Phil

 

Hi guys thanks for the comments.

Ted, thanks for the estimate... that sound realistic to me, I was surprised at the initially figure I found, around .75 of a mm sounds closer to what I might achieve.

Phil,

I was initially going a similar route to what you originally suggested but it presents too many problems given the conditions I am working under. The decks I have are a rough fit and are not ideal templates. Although I have scribed a line from the cabin and console edges I don't like my chances of getting a good fit straight up. I'm not going to be able to play around with to many test fits as the boat is on the water and I can only beach her when conditions suit, its exposed at this end of the bay. The described method allows me to do a couple of things. 1. Adjust the shape within say 5mm tolerances when fitting. 2. I can rivet the deck down to the aluminium brackets I will install on the hulls, avoiding the need to get under the deck to fit it and avoid the need to concern myself with the core at the fixing points.

The track in the main beam is for 9mm slides so I can't get anything in there much wider than that. I don't want to go over the beam because 1. I can't mould from it easily. 2. It has fittings in place and more to come. 3. Its well above the level required for the deck. 4. Its really more weight than the job requires.

I'm not use I understand why putting a solid glass lip into this slot should cause problems? (The composite panel will be way to thick to slot in) That is only the leading edge, the rest of the deck will sit on brackets mounted on the hull and the trailing edge will fit into a lip under the rear beam. Handily the beams are not in the same plane.

You say 6mm edges might be to heavy? How thick would you go? It would basically be a 25mm wide strip of solid glass at what ever thickness is suitable.

The other couple of reasons I want to tackle it this way is that I can rout drainage slots around the edge as required, say 10mm by 50mm long indentations in the perimeter. On top of that I can place fixing points for marine carpet without concern for the core.

I agree re the vacuum bagging and it is just beyond my current resources, this will be a simple polyester hand layup.

Cheers
MBz

 

Beware the taper

Hello Meanz

Tapering a composite panel is a no no unless you increase the density of the core. The shear stress will increase as you decrease the thickness. So it would probably be good to use ply at the end you want to taper. This is a common problem at gunwale joins that are made incorrectly. High density filler like resin and glue powder may be enough.

Can't you get some friends and a car to pull the boat out of the water a bit more so you can do a properly fitted job? I wouldn't like to do this job without being able to fit the panel properly before edging etc. I pulled a Twiggy out of the water with a 4WD and a 20ft long piece of 12 x 2 inch hardwood underneath. Our 38 ft cat was launched and retrieved with 4 box trailer axles welded into pairs and angle bolted between. A 4WD also pulled it out on a mud ramp and up the road. A Seawind 24 would be nice and easy if you have the space to do this.

cheers

Phil

 

Phil, there is simply no commercial space on the water front here. You can't even pull up to a wharf and buy fuel or empty a toilet. The single local slip can't handle the beam of the Seawind and the local ramps are busy public spaces that are not conducive to any work at all. I have to travel to Queenscliff to slip and that means ferry journeys to and from every day just to get that done. Space at home is limited so I can't drag her home even if I had the trailer to to it. Pleasure boating is not that well catered for here, even the commercial boats lug fuel in drums!

I am confident I will get close on the first fit but not so confident that I'd build something that can't be slightly altered.

I understand what you are saying about tapering the core. I was thinking that because its 45 degrees, across 15mm and close to the edge where the cores strength would be less of an issue it would work. The reason for the bevel is simply to get the glass around the corner. I had thought of introducing timber but I am reticent to introduce anything that can rot. Epoxy filler is no good because the polyester will not stick to it and it in turn will not stick to the cut pollycore so ?? Don't forget that the tapered section will have the extra layers of glass on it, so it would be much denser than the main panel.

Mbz

 

Okay

Bugger about the waterfront. Lots of glass should help at the 45 degree part. You could always lay up a nice thick laminate of glass to stick in your track and glue this on to your panels. This would give you a little play.

Anyway - you seem to have it well in hand

cheers

Phil

 

Meanz, at the tapered edge a 2:1 or 3:1 taper is better than the 45degrees, use some qcels & a touch of coloidal silica to make the taper or some core bonding putty like K-lite. To build your solid thickness edge some chopstrand mat will do it & you can taper & stagger this up & onto the ramp of the taper & core, about 5-6 layers of 300 gsm chop plus your 2 layers of 600gsm biax will make up your 6mm thickness. All the best from Jeff.

 

Can I get back to you on that one!

I might just end up with a very big, very expensive skiffle board!

Thanks Phil

 

Thanks Jeff..

I thought that one of the things with this stuff was that nothing sticks to the core itself very well which is why I was going to cut the core at an angle as apposed to trying to get bog to stick to it. It has this scrim on both sides that is the bonding surface but beyond that its supposed to be a bugger to bond too. So you reckon I should build a "bog ramp" ? I suppose that effectively becomes redundant when the glass goes in? It does not have to be 6mm, just strong enough, what do you reckon would be the right thickness?

Cheers
MBz

 

2:1 or 3:1 is better to get the glass around you mean? What about Phils point about tapering the core? or will the choppy be enough to counter that?

 

Meanz, if your using foam, tapering the core would be easy, the polyprop stuff wont taper out nice(although I've never installed any but worked on some already built)), the qcel mix will become a higher density core taper for you. Is 6mm enough? probably but you'll soon find out, are you putting some longtitudinal stringers under too? http://www.proboat-digital.com/proboat/20071201/ go to the contents &check out this groovy link on core transitions. All the best from Jeff.

 

Seems to be getting bogged down in technical PROBLEMS. Go find a couple of "one off" - not production - boat builders, take a sixpac of brown stuff and ask for some advice/help. I have a sample of nidaplast (a plastic honeycomb with glass on both sides), comes in several thickness's and has surprising load carrying strength but comparatively less in impact/point softness - sort of - Go see the guys who work with it and other stuff that may work for your project...

Privately, Heinz, it looks like a new boat project, cheaper and easier in the long run... Good luck...