Sand or Soda blasting ??

[Canuck Dennis]

Am thinking of blasting the hull of my 70 ft aluminum Stephens here in the PNW, down to barrier coat.
Any thoughts on best application ? any "new" methods on the horizon ??

Not looking forward to this....

[jim rosenthal]

Soda is great. I have used it for the bottom of my boat, and also car and bike parts of various kinds. Does a great job, doesn't heat or warp the metal, and rinses off easily. Highly recommend it.

[motoryacht lover]

I had my bottom done a year ago. I had Owl Creek down in florida remove all of the old bottom paint. They did it with sand blasting. I had heard of the concerns about sand blasting and asked some questions. What I heard was that in an experienced hand that sand blasting was fine, conversely in an inexperienced hand damage to the gel coat could well be possible. In the end I relied on the experience of the yard and so far so good.

[34Hatt]

Am thinking of blasting the hull of my 70 ft aluminum Stephens here in the PNW, down to barrier coat.
Any thoughts on best application ? any "new" methods on the horizon ??

Not looking forward to this....


Well since's its aluminum what is the barrier coating?
Usually you would sand blast acid wash then a couple coats of coal tar then bottom paint.

[rwetherington]

We are doing farrow blasting at Jarrett Bay. It is less costly and does not damage bottom.

[jim rosenthal]

Looks like it would be fine. (no pun intended) However baking soda dissolves and can be washed away, which recycled glass cannot. I don't know if the Farrow system recycles the abrasive or not. They also use heated media which evidently speeds the process up. I don't think the soda blasters do that.

Interesting that evidently "glass beading" is not really glass? Farrow abrasive is old glass bottles crushed fine...another interesting use for old glass bottles.

[Canuck Dennis]

Just back form the yard that does glass blasting....he figured to budget 8-10 K for the works including bottom paint...ouch !!

[Avenger]

AFAIK glass bead is really glass. We use it as a blasting media and it is definitely not crushed glass. When it is new it is somewhat light reflective similar to Scotch-lite or other types of reflective tape.

Also, we had the foundation of our house stripped by soda blasting and the Armex may dissolve eventually, but it's pretty stubborn stuff.

[bigbillys]

In the past when restoring aluminum automobiles, we always used soda. Sand blasting hardens the aluminum and makes it more brittle leading to cracking. The ability to wash away the excess is really a bonus on cars, don't think it is much of a plus on the outside of a boat hull.

[Canuck Dennis]

The hull is 5/8" not much worry about cracking, also only going down to barrier coat at the most.

[Boatsb]

Just back form the yard that does glass blasting....he figured to budget 8-10 K for the works including bottom paint...ouch !!

$8-10 K for all of it? Blasting, barrier coating and paint? On a 70 footer is that not a fair price?

[dsharp]

They used to call that sand sweeping. You can get different grits of blasting media that won't remove the barrier coat and fairing material. I would check with the coating supplier and see what they recommend for a surface finish.

[Canuck Dennis]

The breakdown is as follows.. depends on the extent of blasting actually required.

In and out..1250.00 total

on the hard..100.00 per day

in the blast shed..200.00 per day

blaster including mtls..250.00/hr.

bottom paint ..60.00 per hour same rate for epoxy barrier coating.

Paint material at cost +20%

Good yard..two lifts 200 ton ea. used to be Crescent Yachts location.

[Boatsb]

Thats not out of line for a 70 footer except for the daily storage. Then again its all relative.

[34Hatt]

I can't understand spending that type of money and not taking it down all the way?
This is a Aluminum boat so corrosion could be starting under the barrier and you won't know.
If it was fiberglass I could see doing it this way but aluminum boats are a different breed.
Which is why they usually take it down to bare with sand so that you have a rough surface for the product to bite to which helps.
I suggest you go to a Aluminum boat forum and ask the question there on whether you stop at barrier or strip it?

[Canuck Dennis]

If the aluminum is corroding under the barrier coat, the barrier coat loses adhesion to the aluminum and then it becomes a "blister" which can be easily seen.

[34Hatt]

If the aluminum is corroding under the barrier coat, the barrier coat loses adhesion to the aluminum and then it becomes a "blister" which can be easily seen.

I have striped window frames, outboard motors and other aluminum parts and in area's that looked perfect had corrosion starting!
But hey its your call and $$$.

[Canuck Dennis]

If aluminum is corroding on a boat structure, there is a serious issue developing somewhere and if on the underbody then even more serious, I have owned this one since 1991, comes out every year and the only corrosion is where the teak contacts the aluminum or where there is a gap in the continuous welding of seams, so far this has been reasonably controllable and is not an "electrical" issue. zincs are usually minimum 50 % , some even better. There is minor electrical leakage in the Marina but is not regarded as serious. Our salinity here is much less than in the South and our summer water temps rarely go over 75 if even that.The boat was "stripped" in 1989 and re epoxeyed then.

[Werner Schoenknecht]

In 2009 I used the Farrow System with outstanding results. We have a guy with portable equipment and he came to the yard were we store our boat in Northern Michigan. A skilled operator can remove a single layer of paint if so required. The cost for our 1987 43 MY was $4600 which included complete paint removal, two barrier coats and two bottom paint coats. It also included a cut to the yard owners for allowing him to work on the property.
Werner Schoenknecht MIRAGE

[Canuck Dennis]

I contacted Farrow last week..seems they don't recognize Canada as a Country...