My general purpose thread for various questions

[Barnacle Bill]

There are multi season antifouling paints that will be effective after you pull the boat and let the hull dry. Single season cuprous oxide paints are the ones that lose their effectiveness after the chemical change that takes place after the hull dries. I have written a lot about this in the past, I will not go into it now. But, also look into Interlux because they just came out with a new system with different properties and performances.
If you want to just apply an underwater epoxy, try VC Performance Epoxy (not expoxy). It is white and is very hard and is good for the purpose you are speaking of. If you want a colored hull, then you must use a two part epoxy paint designed for underwater use. They are not so popular as they once were. Do not use a one or two part urethane paint as they will blister.
Sandblasting is pretty aggressive and you are better off to use some of the other methods mentioned (sanding, scraping - if it works - or a chemical removal). After you sand a hull, it is advisable to apply an epoxy water barrier paint anyway to prevent blisters even if you us antifouling paint (or not).

 

[kenn]

Re stripping the bottom - after trying several things, I settled on a soy-based stripper. It was effective, lower toxicity than sanding or other strippers, and fairly easy. This is about my 6th time mentioning it, so i suggest you search this forum for "soy stripper" to find out more details.

Our boat has BNC- type RF plug and jack on the RG-58 antenna mast/deck connection. Other than a piece of heat-shrink on the plug, there's no other protection or weatherizing, but this has stood up for maybe 6 seasons minimum without failing. The BNC connectors are designed for 75-0hm coax, but seem to work ok for the 50 ohm VHF antenna.

 

[Joe]

You must use a scavenging vacuum device for any type of power sanding application in our local boatyards... I'm certain it's the same in most other areas of california. I've yet to see any pros using a big disc sander like that...you'd have to completely enclose the boat and then you run the risk of grinding right through the gel coat.

The popular solution has been to WET sand... use an orbital sander with vacuum attached or go with the chemical stripper method.

 

[Sumner]

..... I've yet to see any pros using a big disc sander like that...you'd have to completely enclose the boat and then you run the risk of grinding right through the gel coat....

Hi Joe, the main purpose of that sander is polishing and it isn't a grinder. It will operate at a very low speed and has to provide control or you would polish right through the clear coat on a car's paint and ruin it or if you are sanding the car after painting to have a show quality paint job the same applies. I would replace the 7 inch disc soft foam pad that comes with it with a 6 inch one.

With 80 grit discs you aren't going to go through anything very fast. I used the ......

.....DA which is very similar with....

...... 80 grit discs and had no problems at all and I was sanding the gel coat. Never sanded through it.

I did this inside of my shop and swept the floor when done. I'll admit that if I would of had to go through a number of coats of paint there would of been more on the floor.

Then I would have ...

....put plastic down for the sanding operation. As it was I put the plastic down only for the painting and would have done that first if I would of been dealing with a lot of paint residue from sanding. Use the sander at a low speed you won't be throwing sanding dust everywhere.

I'm just offering an alternative and realize that it might not be for everyone. Some of us don't live near boat yards where we can pay someone else to do the job and have to make out with what we have.

Ruth says hi and hope you have a good New Year,

Sum

 

[dscribner]

Sum,

Not tired of "hearing" from you. You and Ruth have some amazing additions to the boat that you've posted and are a wealth of knowledge. I respect that. My point with the paint is this; why put poison in the water unless you HAVE to? I'm not a tree hugger but I think being responsible whenever possible makes pretty good sense. Also, ablative paint is clearly not intended for trailerables, as my weekly Smurf makeup will attest to. There are alternatives and I think I may have found one. Aquaply M is a waterbased, non-poisonous bottom paint. Hard, tenatious like bull, slick. It is also used for water slides. It has no VOCs and releases no toxins into the water. The drawback to the moored crowd is it's best to dive occassionally to clean the bottom. But . . . it aint gonna kill yah if you do. The paint comes with a decal and cetifcation to that affect. It can be tinted and color matched to SW colors, applied with tip-and-roll, and cleaned up with water. It cost about $220 for a 2 gallon "kit" so it's about the same as EasyPoxy or other single stage finishes. I . . . percieve, that a large sector of the sailing crowd have MUCH deeper pockets that I do and have not problem spending an additional $500 on stuff, when I would have an issue shelling out that much for anything.

 

[caguy]

Sum,

My point with the paint is this; why put poison in the water unless you HAVE to? I'm not a tree hugger but I think being responsible whenever possible makes pretty good sense. Also, ablative paint is clearly not intended for trailerables, as my weekly Smurf makeup will attest to.

From what I understand, the copper used in bottom paint is not toxic, it only deters algae from growing on it. I agree about the ablative mess for on trailerables, that is the reason that I went with the Hard Bottom paint. One gallon was enough for the Cat 27 (two coats) at $109/gal.

 

[kenn]

From what I understand, the copper used in bottom paint is not toxic, it only deters algae from growing on it.

Uh, no, copper-based antifouling paint is quite toxic.

If you're mostly daysailing, or the occasional weekends, and the boat is back on the trailer after each outing, then you don't really need antifouling paint. I stripped the old pooped-out antifouling off of our boat a couple of years ago, right to gelcoat, and I've found that even after nearly two weeks in water, it was fairly easy to scrub off the slight growth (10 min with a hose and a scrub pad) IF you do it right away after pulling the boat out. Let the scum dry and harden and you have a big chore ahead.

This is in freshwater, I don't know what you'd experience in saltwater.

If we kept our boat in-water for extended periods, I'd proibably go for VC-17.

 

[c_witch]

Hiee All,

Firstly thanks again for all the wonderful answers to my many questions. They have helped in so many ways .

Now for my new question does anyone recognize what this material is in the attachment photo?
The bow of our boat has been covered in it both port and starboard and it seems to run aft from the stem about 2 feet or so and gets thiner as it does. The actual FRP is in tack with nary a sign of any damage ie broken matt etc so I am wondering if it was used to fair out the bow?? It runs from the gunwhale to the waterline also. There were/are cracks on both sides to the bow in this stuff that I need to repair.

The piece in the photo's is about 5/8'' thick. Originally I was going to fill the damaged area with cut strand fibreglas and resin but have been wondering about making my own filler with polyesther resin and microballs. In either case layering the repair gradually. I have no idea as to how the damage occured but suspect the the bow sprit was put into a piling while docking or the boat suddenly lurched forward on the trailer for some unknown reason.

Any how thanks in advance.

Oh has anyone use Pettit paint on their boat such as Vivid? and what was the process esp that in doing the bottom.