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DonCig
12-13-2005, 11:52 AM
In laying a metal straigtedge along the bottom of my 18, I see that I have approximately .125" of hook in the last 1" of the hull bottom in the part of the vee that the boat rides on at top speed. I do not currently have any handling or bow attitude issues. The hook is probably from the molding process since the bunk boards run right to the edge of the hull bottom.
Is there any good reason to take an orbital sander to the bottom and make this area perfectly flat and remove all of the hook? Do I need to worry about cutting into the hull 1/8 of an inch?
Should I leave well enough alone?

Thanks,

Don

Lenny
12-13-2005, 01:11 PM
I'd leave it alone Don. 1/8" WILL take you into the first one or two layers of the initial layup in the mold. No biggy really but then you will have to paint or re-gell the area and block it out again. The gel there, even tho at the bottom of the mold and thus subject to pooling and a greater thickness, still is probably only a 1/16 of an inch thick(.06250). .028 being the norm elsewhere on the hull.

gcarter
12-13-2005, 01:18 PM
Lenny, do you need to remove the gel to fair the bottom?
What I mean is, rough up or remove the gel, fill and fair the bottom with glass filled filler and regel?
Or ????????

Lenny
12-13-2005, 01:48 PM
Lenny, do you need to remove the gel to fair the bottom?
What I mean is, rough up or remove the gel, fill and fair the bottom with glass filled filler and regel?
Or ????????

George, if he has to "remove" an eighth, then the gel WILL be gone there, if he needs to "fill" and taper an eighth going forward then no, he will be adding "stuff". Removal can only help but it is so minor, and not across the entire width of the rearmost wetted surface. If you were "adding" stuff to the hull bottom, as in secondary bond, I would be doing it against the matt surface and not the gelled surface and then start the fairing, re-gel, and block. Vinylester fillers (putty's) would be my preferred choice. I can't imagine a bottom being so sadly mis-shaped that you would have to peel it tho. The gel is not uniform on the inside (against the first lay-ups of matt) It can be all over the place and thicknesses so using it as a blocking reference when sanding is not a good idea. What I am saying is, when the mold was sprayed, the fellas could have dumped a 1/4" "pile/blob" of gell in there and you would NEVER know from the outside of the hull looking at it. So to sand down to the beginning of the first lay-up as a reference is NOT a good idea. A straight edge and running water for reflective purposes would be what I would do.

I think he should not bother and his hull won't be upside down to play with either.

GEOO
12-13-2005, 03:35 PM
When I worked on my hull I had 3/16" hook in the bottom of the vee. It seamed to be right under the plywood molded into the bilge floor, for mounting bilge pumps ect.? I layed extra glass in the transom rebuild which went down the bottom too. So I ground the transom to remove the hook, instead of filling the hollow. This added a little rocker, which started about three feet from the transom.
My boat's bottom was a mess. It had 20 years of bottom paint, scratches ect.., so it wasn't a issue of messing things up, it could only get better. I'm not sure if it is worth all the work in a newer boat.

gcarter
12-13-2005, 04:37 PM
I'm really thinking of my Minx. I'll be doing some cleanup and gel work next month. Mine also has 20 years of abuse. But the hook is from the tangent of the large keel radius to the inner strakes, both sides. I thought it might be fun. I think I'm more inclined to fill rather than grind. I think first I would use a straight edge and define the area to be filled, grind off sufficient gel till I'm seeing mostly glass, and then fill and block, before re-geling.
Does this sound reasonable?
Right now it's just an idea, but I will be cleaning up and re-gelling the bottom next month.

Mr X
12-13-2005, 04:46 PM
Don, I would not fool with it.....but if you must.....use an air file......it will be very difficult to get it perfectly straight with an orbital sander.

Lenny
12-13-2005, 05:48 PM
Don, I would not fool with it.....but if you must.....use an air file......it will be very difficult to get it perfectly straight with an orbital sander.

...or a longboard as they did back then...but don't mess with it IMO. Your 500hp will overcome any negatives I think :D

DonCig
12-13-2005, 09:51 PM
Thanks guys. The orbital sander and the flat fille are locked up in the cabinet.
We added a .5 point to the engine compression and removed all the sanding grinding stuff!

Don