Raising Waterline

[swisscraft]

Hi there,

I have a Fiberglass cruiser and the waterline is quit low. Its not in the water but I get terrible growth since its right border line to the antifouling. Therefore I decided to raise the waterline, means paint the antifouling higher without any other modification.

I get now mixed feedback what to do. Its clear to me I have to sand the gelcoat and take the wax off before putting antifouling on it.

Is it really necessary to do more like putting an epoxy primer on it? I'm currently in Grenada and all that epoxy primer stuff cost a fortune. Would be happy if not needed...

Thanks a lot!

[Dragon Lady]

Hi SC,

I have been told if in doubt always apply an expoxy primmer, it may come down to whether or not you are prepared to do the job again if it doesn't stick.

They also say it's all in the preparation.

good luck

[minaret]

Originally Posted by swisscraft

Hi there,

I have a Fiberglass cruiser and the waterline is quit low. Its not in the water but I get terrible growth since its right border line to the antifouling. Therefore I decided to raise the waterline, means paint the antifouling higher without any other modification.

I get now mixed feedback what to do. Its clear to me I have to sand the gelcoat and take the wax off before putting antifouling on it.

Is it really necessary to do more like putting an epoxy primer on it? I'm currently in Grenada and all that epoxy primer stuff cost a fortune. Would be happy if not needed...

Thanks a lot!

Does your current bottom have an epoxy primer/barrier coat on it? If not there is no point in having one at the waterline. If so then I would definitely apply it to the new raised waterline as well. Raising a waterline is an art form, especially on a big boat or a boat with a lot of shape in the ends. I can do most perfectly by eyeball, but my Boss is the best at this. Nothing but a roll of 2" blue. Be careful and find someone who knows what they are doing, I have seen many a hideous waterline. These days we level all boats fore and aft as well as athwartships when they are blocked. This allows us to use a strobing laser on a transit tripod to strike a perfect waterline at any height, up or down. It is not just a question of moving the waterline a set amount up, it is a line on a compound surface. If you move it up 2" amidships you may need to move it up as much as 6" under a counter stern with lots of shape. Same reason a bootstripe has no constant width. Boats aren't flat.

[daddle]

Remove all that barely useless junk that boats accumulate?

[sailorboy1]

I moved my water line up with the anti-foul paint on my last boat. All I did was some some hull cleaner to remove the wax etc and put the paint on.

I wouldn't do anything serious if I was you; you never know you might change your mind.

[Eric M]

For what its worth I did this same thing the last time we had our boat out of the water. I just sanded the gelcoat to roughen it up and painted over it, no primer. I figure the area I was painting is really not underwater so I was not worried about a barrier coat per say. The trinidad SR is still holding on well 1.5 years later with every other month scrubbings by the diver. Glad we did it as we no longer get growth that is hard to remove from the boot stripe.
A trick that worked well, actually really well, was to shoot the new waterline at dusk with one of those laser levels you can buy for hanging pictures in your house. Set it up on a ladder about 15' from the boat and I had a perfect line to follow with the masking tape. I can't emphasise how well this worked to get a perfectly straight line around the curved shape of the hull.
Good Luck!

[neilpride]

A couple of quarts of 2000e interprotect is not so expensive and and the same time you barrier coat the gelcoat and improve the antifouling adesion, trick is when the primer is tacky aply the antifouling.