Working on old kevlar hull?

**Mhall222** · 06-19-2022, 02:45 PM

I picked up this 1978 Berg Maverick last week and I am in the process of tearing it down for a complete rebuild. As soon as I started removing the floor I noticed the cloth this hull was built with was bright yellow. I suspected kevlar but thought this is a butt pile of kevlar in this hull but after some testing of the fibers from a couple samples it sure looks to be kevlar. The threads are consumed with fire where as glass fibers are not consumed but may melt back slightly. This is the only real test I have done to try to verify that it is in fact kevlar. The pictures do little to show how bring yellow the fabric which is even more yellow than the poly foam that was poured around the fuel tank. Anyhow, Lets assume this is all kevlar, how do I prep it for more laminations? Can I use poly or do i need to use vinyl ester or epoxy? I have 55 gallons of high quality GP resin on hand so it would sure be nice to be able to use it. I was thinking of possibly going over the entire bottom, stringers and all with a single layer of 1708 while adding a few bulkheads and ribs on the bottom to stiffen up the lightly built up hull. I understand that vinyl or epoxy is recommended with new layups using kevlar but what about just going over the top of this that is existing which would be a secondary bond anyhow? Also what do I do to prepare the surface for more laminations? I read that sanding kevlar does not give the best results and possibly sand blasting would be ideal? Any tips or info on tackling this would be great. I want to be sure to not hinder or harm the kevlar's strengths by doing something stupid in the repairs or additional laminations.

Thanks
Mike

**Jim Speros** · 06-19-2022, 04:57 PM

Not sure what the experts will tell you but, I will share the little i Know. Kevlar is unique when you grind into it. It furs up. Its so tough is doesn't cut clean like other fabrics. I have laminated with it using epoxy. Not sure what the tricks in prepping are. I do wonder if the structure under it is sound? And if it is why you want to add to it?

**XstreamVking** · 06-20-2022, 03:06 PM

Do a test tab to see if the poly sticks to it. May have been built with it. Most that would go to the expense of kevar would use a better resin.

**Mhall222** · 06-20-2022, 08:25 PM

I have burned and done a sanding test and this hull is for sure kevlar. All this stuff does is fuzz you like crazy when you try to sand it. The original builder's son said something about them using vinyl ester resin with kevlar but would they use kevlar and vinyl ester with wood core? The stringers may be foam core of some kind as I did dig a little out of one hole i found and it didnt seem like wood. I have not tried to cut into one to see exactly what is inside yet but I will before progressing. I guess to be safe I could just use epoxy but man it would sure be nice to use up some of this 55 gallon drum of resin I have. the hull seems sound but I want to add some bulkheads and laminate some foam strips down in a few areas to stiffen it up a little more where I feel it may flex too much. Been stripping off paint before I take it to the shop and start pulling the cap and everything else to start on the rebuild.

**XstreamVking** · 06-21-2022, 06:42 AM

Adhesion test for compatibility is gonna tell you what you can use. No other real way I know of. Or just slap leather and use epoxy.

**FUJIMO** · 06-21-2022, 12:07 PM

...honestly, you can go forward with any resin you want. gp, vinyl, epoxy, whatever. they will all bond to the kevlar no problem if you simply prep it properly. but, personally, since many of the nicer fishboats like these were/are using kevlar in the laminate schedule, i would go with vinyl. its primary & secondary bonding characteristics are excellent. its impact rating is excellent, and on & on. while your in there, make sure all those compartments can drain easily...

**FUJIMO** · 06-21-2022, 12:11 PM

**FUJIMO** · 06-21-2022, 12:15 PM

**FUJIMO** · 06-21-2022, 12:18 PM

**Mhall222** · 06-21-2022, 12:24 PM

I am already putting some thought in how I want to ensure things always drain and drain well. something that bothers me is when washing something out it does not drain or crap does not flow through like it should so all areas that are subject to getting wet or dirty will be setup to drain properly for sure. I want to keep this thing nice and clean inside and out and maybe it will make it another 43 years.

**XstreamVking** · 06-23-2022, 10:09 AM

Being a 78 it might be a AME 4000 boat. Maverick was doing some nice guide boats then where you could still order it how you wanted it. Kevlar was growing in popularity as an option.

**Mhall222** · 06-29-2022, 09:08 AM

Advice is sure going to be needed on correctly fixing all these issues. I have had the bottom blasted to remove the bottom paint and barrier primer and now the cracks that are all over the hull can be seen well. The cracks do not go all the way through into the inside of the hull looking like they stopped at the kevlar? Some of the cracks are just gelcoat but some look like the skin coat may have suffered cracking as well. The strakes are very thin glass like possibly only the skin coat thickness then they were filled with a very hard foam and glassed over with the other layers of CSM and then kevlar. The hull itself is solid and most all the cracking is on the very thing layup on the strakes. The bottom of the hull is very flexible in a few areas mostly in the area behind where the strakes terminate about mid hull. Inside the two main stringers there is very little in the form up support to really stiffen the bottom up. I have plans to add a good bit to the stringer grid to get it nice and stiff after adding a layer or two of 1800 biaxial over the kevlar with epoxy. I think the biggest isssue I am going to face is how to fix the strakes which are extremely thin glass. I am not sure there is even enough thickness to taper a grind back to where you cold lay up new glass. I am almost decided that I will need to glass over the strakes completely or maybe even the whole hull bottom. I want to make sure this is right....This is a super cool hull and I want to be sure to build it back where it can be around another 43 years down the road.

If I was to glass over the whole bottom what would be the suggested fabric to use? I am going to plan on using epoxy for all the hull repairs but unsure what cloth would work best for going over the entire bottom without adding too much bulk. Also if using epoxy can glass be laminated over properly prepared gelcoat or does it still have to be ground down to glass before laminating? I was under the impression that if the base material is solid and it is prepared correctly that you can laminate over it with no issues at all if using epoxy? I have lots of ideas but I am not a professional and I do not know all the little tricks and tips so if anyone wants to share thoughts or advice please do...