Antifoul advice please

Jwmarineuk · 08 October 2013, 20:29

Going to be antifouling the bottom of my 5m Humber.

It is currently antifouled but the job looks quite rough.

The plan was to key the bottom of the bottom and get any flakey patches off.

Then apply the antifoul as you would normally.

I was wondering if it would be best to just antifoul the part of the hull that would be getting submerged or to make it look tidier would it be okay to paint the whole bottom off the hull up to the edge of the tubes and the back of the transom. To give the bottom of the hull one colour rather than having half anti foul and half original hull colour.

what do you think?

Pikey Dave · 08 October 2013, 21:06

Is the boat going to be kept afloat or trailered? If it's trailered, get rid of the antifoul, PITA of a job but better for it.

MikeCC · 08 October 2013, 21:13

If it's over old antifoul, even if keyed, make sure new paint is compatible or use appropriate primer. You don't want it to wash off on the first outing.

You could just paint the transom up to it's usual waterline. At least any growth around that area will be easy enough to remove.

alystra · 08 October 2013, 21:28

Quote:

Originally Posted by Jwmarineuk

Going to be antifouling the bottom of my 5m Humber.

It is currently antifouled but the job looks quite rough.

The plan was to key the bottom of the bottom and get any flakey patches off.

Then apply the antifoul as you would normally.

I was wondering if it would be best to just antifoul the part of the hull that would be getting submerged or to make it look tidier would it be okay to paint the whole bottom off the hull up to the edge of the tubes and the back of the transom. To give the bottom of the hull one colour rather than having half anti foul and half original hull colour.

what do you think?

I would antifoul the bit that's underwater when the boat's at rest, and add a couple of inches to allow for the splash zone. Leave the rest, which I suspect is only a bit of the bow area, as I don't think antifouling paint does well out of the water. It's certainly not glossy like the gel coat. If your Humber's like mine, you'll need to antifoul the after end of the tubes as well. My tubes are navy blue and you can't see the navy antifouling, it's exactly the same colour.

Of course, only do this if you keep the boat afloat during the season, otherwise as others have suggested, get it off.

Jwmarineuk · 08 October 2013, 21:39

Thanks for advice,

There is a guy at the marina who said that due to the age of the rib you'll never get the anti foul off and the hull looking decent again? So best to just re anti foul it.

The boat is kept out of the water.

Maybe the guy was just trying to get some quick cash and he offered to re do the antifoul shortly after!

mick · 08 October 2013, 21:49

Quote:

Originally Posted by Jwmarineuk

Thanks for advice, There is a guy at the marina who said that due to the age of the rib you'll never get the anti foul off and the hull looking decent again? So best to just re anti foul it. The boat is kept out of the water. Maybe the guy was just trying to get some quick cash and he offered to re do the antifoul shortly after!

It's possible I had the same issue mine had a couple of coats on and was chipped but I scrapped it off with a wood chisel hard work you need goggles and a decent mask and then get some cleaner thinners and start rubbing the rest off. I haven't completed mine yet and it won't be like new either but from a distance it's not to bad. Will do more to mine over the winter.

alystra · 08 October 2013, 21:55

Not sure that age has anything to do with it - unless the antifoul is covering up some damage to the hull. However, the general advice when antifouling is to 'key' the gel coat with abrasive, then apply a/f primer before the final a/f coat. To my mind, on a boat such as a RIB this is bad advice, as RIBs generally are kept ashore on trailers and not antifouled.

With a mind to it's resale value, I just cleaned the hull of mine to get rid of any polish and applied the a/f directly onto the shiny gel coat. It stuck well and didn't peel off when under way (around 25 knts average). Yet, if I ever sell the boat on, and the new owner removes the a/f, he will get back to shiny gel coat and the boat will keep its value better.

HUMBER P4VWL · 09 October 2013, 07:02

Personally I'd have thought that if someone wants a rib with no anti foul, whether you say it'll come off easy as you haven't keyed it or not, they'll walk from an anti fouled boat.

Re the re application of anti foul, it's designed to flake off. You could run off old stuff but each year we just re apply with a roller having power washed the hull at end of season.

Humber tubes are pita at rear. Barnacles/weed try their hardest to get on them. Anti foul comes off more easily as it flexes. We ended up putting rubbing strake under the rear quarter. You can then just scrape it off with no damage.