Hand versus Power sanding bottom

[bigmc83]

Hi all,

As I contemplate and daydream of the coming spring, I am still working out my plan of attack on painting the bottom of my Beneteau 37. Owned it new for 2 years, and since the marina hauls out every other year, this is the first time I will be painting the bottom. The original looked pretty good upon hauling this winter. The original bottom coating included 2 coats Interlux epoxy barrier and 2 coats Interlux antifouling (not sure which).

My question is since the bottom appears to be in good shape and the boat not being that old, is hand sanding good enough with 80 grit? I'm nervous to use a power sander such as a random orbital, but I don't want the job to take forever. Thanks for the input.

Sean

 

[Gunni]

Contact the dealer who sold it to you and find out what the boat was painted with. Some paints just need a good scrub, others require sanding. You yard may also have rules about sanding.

 

[bigmc83]

I have the documentation, I will check that or contact my dealer. I don't want to get into the whole bottom paint discussion, but I was interested in using a different brand than Interlux. My yard does have rules about sanding (dust collection, covering work area, etc) I do not own a sander, but have read other threads on here concerning them, so I don't mind picking one up to connect to my shop vac if it will make the job go faster and come out better.

 

[tomgrigsby]

One thing you'll need to know is if the existing paint was hard type or soft. You can put new soft over hard, but you can't put new hard over soft. That may affect your selection of new bottom paint and how much sanding is necessary. Regarding sanding, you'll want to fair in any rough edges/chips etc. Hand sanding will be fine for roughing up, but a machine would be far less work to fair in rough spots. JMHO. Good luck!

 

[BobT]

If you need to remove or level more than a few square feet of paint, rent, borrow or beg a Fein random orbit sander and companion vacuum. Controlling the dust when hand sanding is comparatively impossible, and it's Very important to keep that stuff out of your lungs! (and teeth and eyeballs and hair.)
Festool sanders are also good at catching the dust, and much lighter weight.
Avoid any sander without holes in the pad, it will not collect the dust for you.
The limitation with domestic shop vacs is often the short hose and resulting tip-overs.

 

[noanker]

my yard has rules regarding sanding....i have them sand it and i paint it. costs me $150 for 31'....best $150 i spend every spring

 

[Joe]

Use a drywall screen type sander and a bucket of water. Wet sanding will bypass the dust issues yards object to...

 

[wetass]

Contact the dealer who sold it to you and find out what the boat was painted with. Some paints just need a good scrub, others require sanding. You yard may also have rules about sanding.

Agree - It would be good to know what it was painted with for compatibility and your options about prep will be dictated by the yard.

Here in Washington, its getting harder and harder to find yards that even let you do your own bottom prep (Paint yes, prep no) due to Environment concerns.

 

[Ron Roman]

I agree with Joe.

 

[Daydreamer]

If I only needed to scuff the surface for adhesion of a similar paint I would use the drywall screen wet method.

Since I did the bottom of my 22 last spring without a dust collecting sander, I can emphatically say, get one!

I used an air powered orbital sander to remove the soft ablative in order to apply a hard ablative. I had dust everywhere in my back yard! Even wearing a Tyvec full body suit, respirator, goggles, I still had that stuff in my eyes, ears, nose, hair. aack!

 

[sailaway78]

Power Sanding

I would be very cautious of a power sander, as you don't want to get the barrier coat. May be hard to do with an aggressive power tool, and virtually impossible if both paints are the same color.

 

[Chris Patterson]

A 37 foot boat? Man, you better be eating a whole box of Wheaties to be hand sanding it. My God, I'd sell the boat before I tried that.
You can buy a 25 dollar 4 inch palm sander at walmart, scuff it in a day or two, throw the disgusting paint filled sander in the trash, along with the cats litter box on top of it, paint it, then sail.
A man would have to be utterly incompetent to sand through to the gel-coat with that little handy home-owner sander. And you won't have to take a half a bottle of Aleve from hand sanding afterwards..

 

[Ray Bowles]

I used a 4 inch random orbital sander with a strong dust collecting shop vac to sand 4 different coats of soft bottom paint off our 38' IP. It was a full keel and took 2 very long days. IP applied a sealer coating on the full keel followed by a primer paint coating. I sanded the bottom paint until the primer coat appeared. There was minimal dust that was not collected by the vac but was caught by the ground covering plastic sheeting required for the job.
The painting of the ablative bottom paint was very easy and done in a day.
If someone would have done the sanding and prep job for $250 or less I would have brused him badly pulling my wallet to pay him.
A full keel boat is a scary sight in the Florida mid-day sun.
Ray

 

[Chef2sail]

Have someone else sand it. Its a thankless job. Bottom paint it yourself. I am on the Chessie like you and have had luck with two paints. Microx Extra and surrently use Petit Ultima 60. I get two to three seasons out of each and both are ablatives. I also have a diver go under the boat every 2 months starting in April. 2 coats with extra on the leading edge of the keel and rudder.

Dave

 

[bigmc83]

Thanks for the suggestions, everyone. I will get a quote from the yard for sanding and make a decision if it's worth it. In the mean time I'll be browsing sanders...

Sean

 

[Bob Cronin]

I agree with those who say have it done. I is very tough on your back - and the dust collection is an impossible job.

 

[RichH]

Bottom sanding is an easy job if what you have is in fairly good condition. With good condition, simply get yourself a 'palm sander' with a 'dust attachment' configuration and attach it to a 'shop vac' with *very fine* filter cartridge installed. Simply, with 60-80 grit paper, 'scuff' the old bottom paint and let the 'shop vac' take care of the 'dust'. All you need to do is scuff, you dont have to sand away all the old bottom paint - just 'scuff it' so that there is 'roughness' for the new paint to 'attach'. You'll need a Tyvek suit, rubber gloves and a 'dustmask', etc. Interlux, etc. has videos on the 'web' on exactly how to paint their products: www.yachtpaint.com

For bottom paint in the Sassafrass, or most of the Northern Chesapeake, the 'current' best for use is an ablative paint with 'anti-slime' compounds ... such a Micron Extra. This will keep the slimes to a minimum and prevent massive adhesion of barnacles which can get a 'foothold' in the thick deposits of 'slime'. Georgetown doesnt have 'good flow' of water to minimize the slime build-up. Consider to use a 'barnacle barrier' spray paint on your prop - such as: Petit "Zinc Rich Barnacle Barrier" - spray can. http://shop.sailboatowners.com/prod.php?13063

Also when using any ablative in the Northern Chesapeake, try to get the bottom paint applied 'as smooth as possible' so that you will get an easier 'release' of slimes when the boat gets 'up close to hullspeed'. Use the maximum recommended amount of 'thinner' so you get the most 'flow out' of paint for the 'smoothest' applied surface. The easiest is apply the paint with a THIN foam roller such as the YELLOW 'WEST SYSTEM' rollers used for applying epoxy - expensive and will eventually 'soften' in most ablatives, so buy a few and change out when the foam starts to 'strip off' when painting, apply the paint 'as fast as possible' so the foam doesnt have added time to become 'unglued' from the roller.

Your boatyard will have 'Clean Marina protocols' for bottom painting needs: tarps, dust control, disposal, etc. Also, simply observe the bottom painting going on by 'careful' DIY bottom painters to help your 'learning curve'; Id advise NOT watching the 'yard workers' who usually 'slop on' bottom paint at great expense and usually leave a quite 'rough' surface.

 

[Chef2sail]

Agree with everything Rich has said and will add we switched from Micron Extra which worked well to Ultimate60 with even better results. Seems the slough off occurs at a speed lower than Microns which helps shedding the slime. If you can get a diver on it a couple times a year worth the cost. We are on our third year on a double cost of Ultima60 and may get 4. We are also in te north central Chesapeake.

 

[RAD]

Use a drywall screen type sander and a bucket of water. Wet sanding will bypass the dust issues yards object to...

Takes me less than an hour for a 32 foot boat with the same drywall sander and I use throw away plastic painters drop cloths
I just rough it up for ablative paint