Divinycel question

[ondarvr]

I would think adding catalyst after thickening runs the risk of incomplete mixing.

There needs to some level of competency in one's ability to mix properly. If you do a piss poor job of mixing, then your results will reflect that. The world can't be made idiot proof.

After saying that, while it could be a real problem, it doesn’t often seem to create big problems in the real world. But it does happen.

Epoxy is different because of the mix ratios. Most of the time you wouldn't be able to get one part of it thick enough to be the right consistency after being combined together. So both parts would need to be thickened.

Since epoxy usage is miniscule compared to polyester and VE in much of the composites world, there just aren't as many marketed options for smallish users. And it's almost not profitable to produce putties for the polyester and VE segment because of high production costs and limited sales.

 

[philSweet]

When I worked in the boat yard, we sold all manner of resins and concoctions we whipped up. I made putty in five gallon pails with two gallons of resin, two gallons of bubbles, and two gallons of silica - and yes, it fits in a 5 gallon pail. After mixing it with a stick until it was all in the pail, I slid a lid over a paint paddle, set it up on the drill press on low speed, and went home. Next morning I came in, made coffee, and turned the drill press off. This made a decent cool whip putty that would stick in any orientation. It was the mother sauce of putties. You could coat Divinycel or polyfoam with it as is. It took hardener just fine, but you only used about half as much hardener by volume, (or use the 30% MEKP hardener, not the 50% stuff if available) because the four gallons of putty only had two gallons of resin in it. Usually, if I wanted to adjust the putty with more silica, I would add the hardener first and then the extra silica. The only real trick is to keep your additives bone dry - at least it was a trick in the Florida Keys with 90 degree dewpoints for half of the year and rain most afternoons. I kept a lot of stuff - store bought or emptied from sander dust bags - in old fridges.

 

[fallguy]

If you drill holes for mechanical fastenings you are introducing stress raisers and potential leak paths.If you have sufficient time when doing the job,and you ought to try hard to arrange it,gently attempt to wrap the first part around the hull in the correct location.If they are causing concern already it might be best to cut an extra length to learn with and see how that goes.First you need to mark the location on all the relevant surfaces and then use the trial piece to see if it can readily conform to the shape and can be persuaded to sit where it is needed.If it breaks at the joints you will have the opportunity to think up a way to use the shorter sections in such a manner that the joints are fair and not obvious.With thick foam it isn't always practical to use a heat gun to make the foam conform as it is such a good insulator and at worst you may have to make a bending former away from the boat to create sections that are shaped to suit and which will immediately sit in the correct location when taken to the boat.Once the mating face is bonded into place and the foam glassed over,you should be ready for refinishing and launching.Once on the boat,be prepared for local damage but losing the whole piece shouldn't happen as you are hardly likely to hit a piece of debris that has the precise shape to make even contact with the whole surface at the same instant,but small pieces of flotsam may leave individual dings for later filling.With an already watertight surface beneath the foam,it shouldn't matter,screw holes or bolt holes make the situation worse.With two or three plies of glass over the foam the total bonding strength is huge and need not extend too far over the original surface.A light cloth as an outer laminate will make the cosmetic part easier.

I put a small piece of light 6-10 ounce glass tape over the outside. Then, I reinforced the radiused edge with milled fober thickened resin.

I think I’m gonna have to mechanically fasten them a bit.

I have 80 feet and lotsa work into it already. Way past the point of adding glass.

If I put a pan head screw over a one inch fender washer, I can lay some 5200 right over the fastener.

Done enough of this sort of thing to know tape ain’t gonna hold it well enough.

 

[wet feet]

If you've glassed the foam before inducing the shape of the hulls you may be heading for a disappointment.Do keep in mind that having a hull surface that is derived from a conic will only be relevant if you are wrapping the new parts around a curve that is perpendicular to the axis of the conic.Even then you will be asking for quite a deviation from the relaxed state in which the glass was applied.If the amount of glass over the foam is much less than the hull layup,you will inevitably have a protrusion that is more likely to succumb to impact damage and the geometry of having the new surface projecting almost square to the local flow of the water will increase the severity of any impact from flotsam.

 

[Skip Johnson]

You might be able to forego some of the mechanical fasteners by clamping the strips down using some ratchet straps wrapped around the hulls and some premade wedges. I think such an approach would require several extra hands to implement.

 

[fallguy]

Hulls are all dev panel; not too worried about shapibg other than compounding at the bow.

 

[fallguy]

You might be able to forego some of the mechanical fasteners by clamping the strips down using some ratchet straps wrapped around the hulls and some premade wedges. I think such an approach would require several extra hands to implement.

Mostly worried about the chaos of greasy adhesive and long length and angled face.