New Aluminium Owner with Questions

[thaisail]

I own a Kanter sailboat. It is a one off Ted Brewer 36 foot cruising boat built in 1982. I wanted to know what you are using for bottom paint. I am located now in Phuket, Thailand and I need to put antifouling. Since I have now run out of TBT bottom paint, I now have to switch another paint without copper. Unfortunately all the aluminum hull antifouling paints available have a poor reputation for a boat that spend a lot of time on her mooring in our shallow water anchorage. If you have heard of any new ideas on how to avoid using copper based antifouling with a thick barrier coat to protect the hull, please let me know. Also, I need to replace my anodes that I suspect are made of zinc that were fitted by the former owner. They have been on the hull for the 8 years that I have owned her and only about 10% of the anode has wasted. I have been advised to change to Maganese but cannot find the right shape anode to fit my four anode attaching places on the hull. Do you know of any other forums for aluminum boat owners where I can find more information?

[noelex 77]

Welcome to forum thaisail.
Zinc is the correct anode material if the boat is kept in salt water. If the anodes are only worn by 10% they don't need changing.
We use Trilux 33 antifouling. You need a good expoxy barrier coat on the aluminium first if you have a look at international paints we'd site they have all the details.
There are some new non metallic antifoulings that look promising, but I have not used them.

[GordMay]

Greetings and welcome aboard the CF, thaisail.

[ice]

Originally Posted by noelex 77

Welcome to forum thaisail.
Zinc is the correct anode material if the boat is kept in salt water. If the anodes are only worn by 10% they don't need changing.
We use Trilux 33 antifouling. You need a good expoxy barrier coat on the aluminium first if you have a look at international paints we'd site they have all the details.
There are some new non metallic antifoulings that look promising, but I have not used them.

absolutely correct on all points:

Zinc
Trilux 33
good epoxy barrier coat

[thaisail]

Originally Posted by ice

absolutely correct on all points:

Zinc
Trilux 33
good epoxy barrier coat

The results that I hear from the boats that used Trilux 33 here in Phuket are very poor. Most report that the paint will only work for 6 months. After that barnacles will begin to attach. The cost of Trilux 33 is 3 times greater than copper paint and only one third as effective. Our boat spends a lot of time on her shallow water mooring with only 1 foot of water below her keel at low tide.

Please can you tell me what kind of results you are getting with Trilux 33? I would like to use Trilux but I cannot afford to haul out every 6 months. The paint contractor wants to add 3% TBT and maybe this will help. We can still buy pure liquid TBT from a small shop in Penang, Malaysia.

[atoll]

you want to do a bit more reasearch,tbt is the only paint to use on alloy,trilux is absolutly useless for tropical waters.

tbt is banned in europe and the us for small vessels but still available for bigger vessels,check the ship yards,what ever you do do not use a copper based anti fouing on alu.

[Celestialsailor]

Originally Posted by atoll

you want to do a bit more reasearch,tbt is the only paint to use on alloy,trilux is absolutly useless for tropical waters.

tbt is banned in europe and the us for small vessels but still available for bigger vessels,check the ship yards,what ever you do do not use a copper based anti fouing on alu.

I was questioning that myself. Regardless of the barrier coat I would think there would be electrolysis between the copper and aluminum. Back in the 80's, I purchased TBT from a couple of guys that bought bulk military surplus paints. It lasted 4 years.

[foolishsailor]

Sadly trilux 33 is the only viable solution.

As your boat is an older one, like mine, it is even more important to do the hull correctly. Older hulls have an infinite number of microabrasions and a highly microtextured surface. This can increase the effective surface area by as much as 20% and makes older aluminum hulls highly suseptable to issues with copper paints.

A properly prepared well bonded barriar coat with trilux 33 is the only real solution for long term viability.

Minaret should be along shortly to give some good advice

[foolishsailor]

I am getting ready for a full strip and repaint of my hull in a couple of months and here was some great advice I got from Minaret, who is a pro-builder on this forum.

You can see he recommends using Trinidad SR vs. Trilux 33 and I am seriously considering it...

1. Sand blast with medium mesh silica sand. Blast bright to a profile of 3-4 mils. Alternatively, if you can't find a good blaster, chemical strip with aircraft stripper, wipe two rag technique with 202 twice, and grind 36 grit. If you have thin plate you might step the profile back to 60, though manufacterers specs state 36 profile.

2. Etch with Alumiprep 33 immediately. Clean after blasting only with carefully filtered high pressure air.

3. Passivate with hexavalent chromium conversion, use Alodine. Follow instructions carefully.

4. Apply a slightly thinned (10%) coat of Interlux 2000e. Use 2316N. Apply with a 1/4" candy striper on a 9" frame. Roll nice coats carefully.

5. Apply a coat of 2000 neat. Wait 24 hrs.

6. If any fairing is required apply Interfil 830 by chemical bond to the 2000. Board fair with 80 grit. Apply 2 coats of neat 2000 to any areas of fairing.

7. Apply a final coat of 2000. This is one more than the manufacterers requires, but provides a nice even finish and is generally required to catch the bonding window of the bottom paint.

8. I know you race, so if you are trying to achieve a race bottom let the 2000 cure for 48 hrs and then sand to 180 profile. If you are a total racing geek trying to develop true laminar flow board fair to 180 with a flexy board. If you are more sane than this, catch the chemical bond window by following the instructions carefully (thumbprint test). Apply the bottom paint of your choice, first making sure it is compatible with 2000 (most are). I prefer Trinidad SR.

9. If you have sanded the 2000 for a race bottom, you will either want to spray the bottom paint with an airless or roll 3 coats instead of two and then wet sand it. You can take that as far as you like, but unless you use a hard race paint I wouldn't go further than 400 wet, there's not much point.

I realize this advice involves mixing products from a number of manufacterers, which may complicate any warranty issues. But my experience has been that no manufacterer will do anything for you anyway, other than sending you some free product, which is of course no help at all. This recipe is what has worked for us, we have been using it for many years. If you do some serious research you will find we are not the only ones. It's a great combo for aluminum, especially below the waterline, as the barrier coat prevents any moisture from getting through and causing the alum to chalk up. It is the most long term solution I have found for aluminum. I have painted some very nice boats this way with no warranty issues.

[atoll]

http://www.epaint.net/NAVY.pdf

try to get hold of some e-paint!from the us navy

http://www.epaint.com/products/19

[atoll]

Originally Posted by foolishsailor

I am getting ready for a full strip and repaint of my hull in a couple of months and here was some great advice I got from Minaret, who is a pro-builder on this forum.

You can see he recommends using Trinidad SR vs. Trilux 33 and I am seriously considering it...

after going to all that expense!

you might want to read this
http://www.cruisersforum.com/forums/...lem-23255.html

[atoll]

another interesting link here
http://www.cruisersforum.com/forums/...ull-30441.html

[atoll]

Originally Posted by foolishsailor

Sadly trilux 33 is the only viable solution.

As your boat is an older one, like mine, it is even more important to do the hull correctly. Older hulls have an infinite number of microabrasions and a highly microtextured surface. This can increase the effective surface area by as much as 20% and makes older aluminum hulls highly suseptable to issues with copper paints.

A properly prepared well bonded barriar coat with trilux 33 is the only real solution for long term viability.

Minaret should be along shortly to give some good advice

another option might be using this proven paint system if you are going to sand blast etc

Sigma Coatings - Marine, SIGMAGLIDE, ultimate fouling system

[foolishsailor]

Thanks for the links, will look into them...

[thaisail]

Originally Posted by atoll

http://www.epaint.net/NAVY.pdf

try to get hold of some e-paint!from the us navy

http://www.epaint.com/products/19

The last time I checked, epaint was only available in the US. I am in Thailand. Also I a not sure how effective this paint would be in shallow tropical waters.