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View Full Version : Lenny.....HELP!!!!!!!



gcarter
02-22-2005, 06:08 PM
Today I started working on the Minx's engine hatch. Before I bought The Minx, the latch had failed and it had blown over on the aft lifting ring. This is the last part of the boat that still looks like a cow pattie.
So I cut away some of the balsa coring till I had removed all the rot.
I then ground the back side of the hatch around the hole. :smash:
What I found was some sort of filled resin (microballoons?) between the skins.
Now I know how to attach a surface on the exterior side to "work" to and lay up the skin mostly cloth w/ a little mat.
Then should I replace the filled area? Maybe some microballoon filled resin faired to match?
I had bought some 1/2" end grain balsa but this is 3/8".....oh well.
Anyone have about 1 1/2 sq. ft. of 3/8" end grain core material?
So help me out Lenny. Take a look at what I've done so far and cretique please.

Lenny
02-22-2005, 07:59 PM
George, what you are seeing is "coremat". There are a couple pics below of it.

It is basically a polyester "diaper" , perferated to assist in resin soak-up. It is an EXCELLENT veil to nullify print-through and provides excellent surface hardness, extremely rigid, (as in no spring to your hatch so that you can walk on it and not ruin it) BUT, it is very brittle and provides very little strength. It is NOT a substitute for a well cored/layed up hull. It simply adds rigidity and builds up thickness fast. There is NO knit or direction stability to it. It comes in (here) Mil thicknesses (as in millimeters) basically 2-3-4-5 mill thicknesses.

It soaks up a ton of resin, and as I said, is a great barrier for print through. It was probably put there to stiffen the hatch as well as be a veil to nullify the print-through that could have been possible since the balsa was not "bedded" otherwise. This became the barrier between the lay-up of your hatch and the balsa. They recommend a putty under a balsa core job in most cases to facilitate a nice foundation for the balsa as well as print-through. This would have sufficed both needs.

I would cut out a section with a router or something, make a rectangular template (like a picture frame) and use a patterning bit in a router and run it around the area to create a very neat rectangular depression. Then taper the sides of the cut-out much like you already have. Contact cement a chunk of Formica (gloss scrap from a countertop shop, they will gice it to you, and wax it up, don't wipe it off (the wax) and hold it on there somehow (contact). Paint brush in some white gel-cote into the hole area, and let it kick. Keep a fan blowing on the gelcoat patch so it doesn't get "Elephant feet". When that is done, (4 hours) lay in some 1 1/2 oz mat (not cloth), say two layers, each one a bit smaller in area. Run these out to the taper and gradually come back in. Keep the fan on this till it kicks. Then lay in another 1/2 oz mat, then a roven patch, another mat and one more roven. Then buy some 3mm core-mat (a yard or whatever) and mix her up and lay it in. Then, say a 1oz mat or 1 1/2" mat on top followed by a chunk of 3/8" balsa. I would spring for it if I were you. It is probably only about $25-$30 for a 2' x 4' piece there. The coremat will be peanuts. In general boats of this size (well built) are variations of ...Gel-coat, 2 mats, a mat and a roven, a mat and a roven. Then you can get stupid about it. If you can, remove another little bit of the damaged area as in a "hole saw" and clean it up a bit. Take this little chunk of scrap glass (even a 1" square) and set it on fire. What is left will tell you how they put it togther and you already know the Coremat balsa game. ;)

Call me if you want to chat about it. :)

250-474-4005 :)

gcarter
02-22-2005, 08:12 PM
Thanks Lenny.
As soon as I get everything rounded up, I'll give you a call.
Would putty be a better solution than the coremat? I was thinking it's such a small area it might be easier.

Lenny
02-22-2005, 08:17 PM
Putty is probably easier, be sure to bed the balsa when the putty is wet. Be sure the balsa is well soaked prior to placing it in there. Either way it is pretty small and minor. Just be sure to get the lift ring hole area built back up to adequate thickness.

...oh, and, get some lift supports/rams :D

I know how easy it can happen. I have "looked" at my motor running a couple of times now, in the ocean, and ended up holding it in my arms and almost going overboard. The reversed pintals for the engine hatch are not such a bad idea either. I can't imagine what yours weighs. :eek:

gcarter
03-15-2005, 07:44 PM
about three weeks after asking. I've been working on this several hours on most days. I've never fooled w/ coring materials before although I've read about the subject extensively.
So here's some pics of the progress.....
If you have any critiques, please let me know. You never know when there will be a next time. I can always use all the help I can get.

gcarter
03-15-2005, 07:50 PM
Here's a few more. The last two are of the inside w/ white bilgecoat and the outside w, the stripe painted. If you look carefully, you can see the reflection of the wall in the paint. All I have left to do is finish color sanding the gel and mounting the hardware.

MOP
03-15-2005, 08:13 PM
Excellent job looks fresher than new!

Phil

Lenny
03-15-2005, 09:05 PM
nice... :yes:

gcarter
03-15-2005, 09:14 PM
Thanks Lenny and Phil! :biggrin.: