Sandblasting a keel

[rgranger]

Well this is going to be a restoration thread.

I picked up my new-2-me Balboa 26 last weekend and I'm just about ready to drop the keel and sandblast it. The keel weighs 1200lbs so I'm a bit intimidated.

Here is what the keel looks like now and I'll post pics along the way. I'll also need to cut away some fiberglass where the PO glassed over the pivot pin (see pic).

Here is what I've done so far...

Today I found an engine hoist for $75 on Craigs List. I'll use that to hold up the keel while I'm working on it.

I also drove to Harbor Freight and as fate would have it they have a 5 gallon sandblast hopper on sale for $38 and they are also running a special on compressors, $178 for a 6 gallon compressor with 125psi ability. I only need 90 psi so this should work. I've never done any sandblasting before so I'm really looking forward to that part of this project. And thanks for the concern... yes I know about siliconosis of the lungs. I have a really good respirator.

The next thing on the list is to build a cradle with wheels to drop the keel into... so I can then pull it out from under the boat and hoist it up with my engine hoist. I'll start posting pics then. I found a pic of someone who has done a similar job on a Catalina 25 and here is the pic of his cradle. I'm going to model mine after this one.

If you have pics of a keel cradle that you have made, I'd love to look them over.

My plan is to finish the job and put the hoist and sandblast equipment back on Craigs list (I'll probably keep the compressor). I'll also try and keep a running total of cost along the way.

By the way... If any of you are considering a Balboa, I'm very impressed with the construction. All of the reviews I found said it was stout... and boy they were not kidding. The hull is thick and there is no give in any of the panels when I push on them. Inside or outside of the boat.

I think that once the keel is resurfaced, I'm going to have a first rate sailboat.

Fair winds,

r

 

[sailaway78]

I hate to bust your bubble

I hate to be the one. I doubt very seriously that compressor is gonna work. It may put out 125 psi, but it will not put out enough cfm to get the job done. Unless you wanna sand blast for a minute, and wait five or more for it to fill the tank back up. I would recommend that you call around and see if you can find someplace that rents soda blasters. These things are neat, and there is nothing to clean up but baking soda, and whatever comes off the keel.

 

[finding41]

Yep. The compressor is too small. I have a small hand held sand blaster (Holds maybe 2-3 cups) and a 15 gal with a 5hp gas engine. It can't keep up! It works ok for my roofing nailers. It will run 2 but has to work hard.

How is the trailer held together? Are the cross members bolted to the outside? If so I would look at just dropping the keel down as far as you can instead of taking it right off. No need to take the boat off the trailer either. Just an idea... I'm kind of lazy so I'm always looking for the easiest way to do something...
When you look at it how much of the top of the keel will be missed... Or drop the front of the keel after the back is done. No need to take it right out and put it on a work bench...

 

[kloudie1]

Yup.. as Easy says, best to rent a rig.. for general around home blasting, ya need about 8-10 CFM (cubic feet per minute).. Lots small compressors are 2-4.. The CFM specs are with the blaster and the compressor.. They have to be rated at the same pressure too. (4 CFM at 40 psi is very different from 4 CFM at 80 psi)
There are some contractors who will come to your house and do the blasting..
OR take it to a sand blast yard and have it done there.. That is probably the cheapest option.. for blasting..
An 8-9 inch side grinder and some 80 grit is the cheapest !

 

[rgranger]

Thanks Guys for the CFM info....

I did call a place that rents equipment. It is going to cost $300 for 24 hours. Seems like I can guy what I need for that price. I'll check out the CFM info and make adjustments. I did a google search for places that will do the sand blasting for me. Couldn't find a place local.

Findings: As far as dropping the keel front and then back and doing each piece ... that would be great! But I only have a few inches of clearance between the keel and the axle. But now that you mention it. Maybe I should look at what it would take to raise the boat up a foot or so on the trailer. I might be able to just put some boards across the rollers and gain the clearance I need that way.

Thanks for the help guys.

 

[Sprega]

Keel removal

I was able to drop the keel out of a northwest 21 by jacking up the whole trailer with the boat on it. I then unbolted the axle assembly and rolled it forward out of the way. Next, I dug a hole under the keel area in order to get the extra room I needed. It worked fine for me, may not for you. In the old days it was commen to dig a hole to drop center boards into. Good luck

 

[rgranger]

Thanks Sprega

That is a good idea but as I think about it more. I think I want to fully remove the keel, blast and treat the metal with phosphoric acid etc. barrier coat it, cover it with some fiberglass gel coat and inspect and repair the bushing. I don't think I can do that while crawling under the boat. I'm thinking this might be the boat I keep for a longer time, so I want to do it right so it will last a long time.

I also have a duel axle trailer so taking off the axle(s) would be a bit more work.

 

[TLW]

I fully understand your wanting to do a complete and first class job, but you may want to skip the gel coat step. Your barrier coat will be epoxy and most gel coats are polyester. Polyester does not "take" well over epoxy. It works the other way around, however. Regardless, antifouling paint over the barrier coat is the norm. The gel coat step is not needed. There are ways to do this if you insist, but your need to research it thoroughly.

 

[Chris Patterson]

Just for the heckuvit, I looked in Roanoke for sandblasters, and there are nine listed. I promise you that it will be WAY easier, and cheaper to load that keel up, and take it to one of those that does sandblasting on a larger scale. A lot of those guys are using Ingersoll-Rand compressors, that deliver 175 cfm's, that will make quick work out of that keel. The price of ANY decent compressor, and the sand/glass/media, etc, will far out price just having it done. And like said, with a home compressor/sandblaster, it will takes days to do it, whereas a big unit will take 30 minutes. Trust me, been there, done that, blah, blah, blah....

Oh yeah, the last hunk of iron I had done here cost me 30 bucks, while I waited. (For thirty minutes).

 

[rgranger]

Just for the heckuvit, I looked in Roanoke for sandblasters, and there are nine listed. I promise you that it will be WAY easier, and cheaper to load that keel up, and take it to one of those that does sandblasting on a larger scale. A lot of those guys are using Ingersoll-Rand compressors, that deliver 175 cfm's, that will make quick work out of that keel. The price of ANY decent compressor, and the sand/glass/media, etc, will far out price just having it done. And like said, with a home compressor/sandblaster, it will takes days to do it, whereas a big unit will take 30 minutes. Trust me, been there, done that, blah, blah, blah....

Oh yeah, the last hunk of iron I had done here cost me 30 bucks, while I waited. (For thirty minutes).

Thanks Chris

Roanoke is only an hour away, I could make a day of it. I'll look into that.

r

 

[py26129]

Thanks Chris

Roanoke is only an hour away, I could make a day of it. I'll look into that.

r

Another option that worked well for me, when I stripped the keel of my PY26 down to bare metal was an angle grinder with a heavy duty brush. It took less time than I thought, angle grinders are cheap and the PY keel looks ot be bigger tha the one on the Balboa.

(The pic above was taken before I bit the bullet, stripped the keel and coated it with POR15. The Tremclad was a tuly bad experience.)

 

[rgranger]

Aother option that worked well for m when I stripped the keel of my PY26 down tobre metal was an angle grinder with a heavy duty brush. It took less time than I thought, angle grinders are cheap and the PY keel looks ot be bigger tha the one on the Balboa.

Yeah... that is a BIG keel!

 

[cactusmitch]

I did this, just lowerd the keel, after raising the boat. I used a scaffold to raise the stern then the bow supports.

 

[Merlin Clark]

I'd skip gelcoat too.
When I bought my Chris Craft Carribean there was a large area (2'x3') where the bottom paint had fallen off because the gelcoat was too smooth! It's be a shame to make it all nice and smooth and then have to abrade it to get paint to stick.
As for the barrier coat, I'd bounced the question around about using coal tar epoxy for this and got a lot of positive responses. It's way cheaper than name brand barrier coat if you shop around.

 

[rgranger]

I'd skip gelcoat too.
When I bought my Chris Craft Carribean there was a large area (2'x3') where the bottom paint had fallen off because the gelcoat was too smooth! It's be a shame to make it all nice and smooth and then have to abrade it to get paint to stick.
As for the barrier coat, I'd bounced the question around about using coal tar epoxy for this and got a lot of positive responses. It's way cheaper than name brand barrier coat if you shop around.

Thanks Merlin

I followed that thread on the coal tar epoxy... it was an interesting read.

 

[rocksculpter]

Small sandblaster and or water

I use the Harbor freight blaster with a 2hp (real) compressor by ganging a series tanks made from propane bottles and a water tank. You get to blast awhile then wait for it to catch up. I blasted all of the gelcoat off my Norsea 27 by using a sandblast attachment on my pressure washer. It was much faster than air but you do go through alot of sand.

When I did that job on my Venture 25 I found I needed a an amount of bondo to fair in the rough cast surface. What ever you do for finish, especially if you use epoxy, use a two part epoxy primer like Intralux 2000 if you want your bottom paint to stick.

Barry

 

[rgranger]

I use the Harbor freight blaster with a 2hp (real) compressor by ganging a series tanks made from propane bottles and a water tank. You get to blast awhile then wait for it to catch up. I blasted all of the gelcoat off my Norsea 27 by using a sandblast attachment on my pressure washer. It was much faster than air but you do go through alot of sand.

When I did that job on my Venture 25 I found I needed a an amount of bondo to fair in the rough cast surface. What ever you do for finish, especially if you use epoxy, use a two part epoxy primer like Intralux 2000 if you want your bottom paint to stick.

Barry

Thanks for the info Barry