Hull Cleaner

S

Sunfish65

Member
Hi,

I have an old hull that I would like to begin work on (when the friggin snow goes away and it warms up!). I would like to give the hull a good cleaning. There are 2 rust stains on the hull below the waterline.

I saw "Starbrite Hull Cleaner" at our local hardware store. Will this get rid of the stains? Will it damage the colored gelcoat that's on my deck (Yellow deck with stripe) if I spill some on the deck? Can I clean my deck with it too, without any damage to the gel coat?

Sunfish65.
 
I recently cleaned a boat that was mildewed and pretty nasty from years of outside storage. I went to my local Bass Pro shop and explained my project. The retailer said he did not have any boat cleaner off the shelf for what I needed. He sent me to the repair section of the store and they sold me something that I needed protective eyewear to use. I delluted it, sprayed it on and lightly powerwashed. It worked great! I have thrown the bottle away so am not much help on the product, but my point is you probably need to find something with an acid base. It did not harm my finish at all. If I can come up with the product name I will post again.
 
Gel coat is porous so stains tend to go deep. Supposedly oxalic acid can penetrate the gel coat and bleach or remove the stains. I've never used it. If the boat isn't scratched up too bad, you might try an abrasive cleaner like Comet with a green scotchbrite pad. Then follow up with a light buffing compound and a buffer with a foam pad. The scotchbrite pad and Comet will remove a tiny bit of gel coat buy not too much. It will definately dull the shine so the follow up buffing would be necessary. I just finished cleaning up an old Sunfish and I skipped all the above. Went straight to sandpaper, primer and marine paint. Looks beautiful in the morning sun!
 
When it warms up, clean the hull with soap and water then sponge on 100% household bleach, let sit for 15 minutes or so and then hose off. Be sure to wear gloves and eye protection and wear old clothes that you don't mind getting discolored from the bleach.
If you still have rust stains, get a household cleaning product called CLR (Calcium, Lime, Rust). Apply it, let sit for a time and wash off. Both of these products are fairly cheap and effective - in fact, you may be somewhat amazed with how well they work. If both fail, consider FSR (Fiberglass Stain Remover) available at Boat US or West Marine. It is pricey but works well for rust and other stains. DO be careful about getting these products on your skin and especially eyes as they are all caustic. Wash the hull with plenty of water and then consider polishing with 3M Fiberglass Restorer, a mild abrasive + wax.

Have fun - painting should be the last option as no paint holds up as well as the original gelcoat.

Alan Glos
Cazenovia, NY
 
All good advice.
Basically, start with a gentle household product. I know that West Marine needs to improve its performance, but there is no need for a more expensive 'marine' product for the initial cleaning. Alan suggested soap, rhr suggested Comet with Bleach and I am suggesting Soft Scrub with Bleach. And use elbow grease in the form of a non-scratch pad. If stains remain, you can try diluted bleach (Clorox), Bar Keepers Friend, or oxalic acid. Or the other products that Alan recommended.
If you are planning on using a powerwasher, use a 'gentle' setting.

PS: As an aside, I personally don't care whether my Sunfish is shiny; I just want to sail on a boat with a smooth bottom that doesn't leak.
 
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