Gelcoat Application Questions

[76SeaRay]

I have three different areas that I need to apply gelcoat over the old gelcoat, Deck/Hardtop, Vertical Transom, and Bottom. I expect to spray the gelcoat on the Deck/Hardtop since they are flat horizontal surfaces for the most part. The questions I have are on the other two surfaces.

Vertical Transom -- The current gelcoat doesn't seem to be real porous but it is thin in places so I want to get it recoated before I mount the gimbal housing. The transom is fairly large (7.5 feet across, 2.5 feet tall at the sides. and 3.5 feet tall at the center of the V. Is it better to spray or roll on gelcoat in this case since it is vertical (14 degree angle)?

Bottom of Hull -- I plan to take the boat off the trailer in the next month or so to get at the bottom. It is pretty porous so definitely needs a new coat. I don't see a way to spray this since I will have to lay on my back to both sand and paint. The boat is large enough that I can't turn it up on the side to spray the bottom. Will roll on gelcoat work best in this location?

 

[Scott Danforth]

spray

spray

spray

use Duratec 904 additive to make the gel spray like paint
start about hear on my thread https://forums.iboats.com/threads/1988-rogue-2420.486013/page-9

 

[76SeaRay]

I am not the best painter in the world so am concerned about runs in the vertical surface of the transom with spray. I have a gravity feed gun with large nozzle for gelcoat though.

When it comes to the bottom, what kind of gun do you use to spray up from the bottom? I don't have a pressure pot but have gravity feed and an old suction type guns.

 

[Scott Danforth]

I used a cheap vapor brand HVLP from amazon with a 2.3 tip. I had a creeper on the ground to move around an my buddy was there mixing and keeping the hose from tangling

Spray from bow to stern under one side,repeat on other, then spray transom

20 minutes for coat, 2 minutes (one beer) break then 2nd coat..... Then 3 or 5 beers while cleaning the gun, etc

Then I did some bunk work on the trailer for about an hour. Then backed the trailer back underneath

 

[76SeaRay]

Thanks. Sounds like a plan. I have one of those same guns. Did you use Duratec on all coats or just the finish coat?

 

[todhunter]

Scott, what about using something like 3M PPS cup liners when spraying gelcoat? I'm just wondering if not having to clean out a cup every time is worth the added cost. I already use PPS when spraying contact cement. For that I think they are worth it because that stuff dries quick and they reduce how much xylene I have to use during cleanup.

 

[Scott Danforth]

Thanks. Sounds like a plan. I have one of those same guns. Did you use Duratec on all coats or just the finish coat?

All coats.

I tried spraying the engine cover without it - it sprayed like manure, spent more time sanding the engine cover than the remainder of the boat

 

[76SeaRay]

Following up as the weather is getting warm enough here to do the gelcoat work. I have two additional questions.

First, how much gelcoat to mix up for spraying an area 4ft x 8ft (32 sq ft) with one layer?

Second, how long to wait before spraying the second layer of gelcoat (with Duratec)?

Third, I intend to spray one layer of unwaxed straight gelcoat and then one layer of gelcoat with Duratec. I just read that Duratec shouldn't be used below the waterline. If I spray my transom, the lower edge of course will be in the water when moored for short periods of time (couple days at a time). Is this going to be a problem and should I not use Duratec on the transom?

 

[Scott Danforth]

I sprayed the hull in 3 phases.

Sides below the rub rail
Bottom
Top above the rub rail
Cockpit

About 20 oz of mixed gel/duratec to cover the 32 sqft

I did roughly 1/2 gal of blue, 1/2 qt of. Red, 1/4 qt of black, 2 qts of grey, 1-1/2 gal of white, and 2-1/2 gallons of 904 ro spray my boat.

When I did the sides, i sprayed the blue first, spray one side, spray other side, repeat. Did not stop

When I sprayed the bottom, did the same. Spray one side, spray other, repeat.

Same goes for the top and interior

I wouuld spray all layers with dutatec. Without it, it sprays like manure and you have to sand. But that is my experience

 

[76SeaRay]

So, I believe Duratec says 50% gelcoat and 50% Duratec (1 to 1) so for 32 sq ft its 10oz of gelcoat and 10oz of Duratec for a total of 20oz for your estimate. How many ounces of MEKP for that mix?

 

[Scott Danforth]

So, I believe Duratec says 50% gelcoat and 50% Duratec (1 to 1) so for 32 sq ft its 10oz of gelcoat and 10oz of Duratec for a total of 20oz for your estimate. How many ounces of MEKP for that mix?

I played with the mix of duratec and gel before hand (per the instructions). with white is was 1:1, with some of the other colors it was 1:0.8

I mixed 1.5% which on some days was a hot mix here in Florida

 

[76SeaRay]

So if my math is correct, that's 8.87cc for the 20oz mix. I just realized I screwed up though. I bought a gallon of gelcoat and a gallon of Duratec some time ago and then got delayed in doing the gel work. I didn't think about the shelf life and time has flown by so both of those are over a year old now. Its only about $400 to throw away, that's just great.

 

[Scott Danforth]

So if my math is correct, that's 8.87cc for the 20oz mix. I just realized I screwed up though. I bought a gallon of gelcoat and a gallon of Duratec some time ago and then got delayed in doing the gel work. I didn't think about the shelf life and time has flown by so both of those are over a year old now. Its only about $400 to throw away, that's just great.

not sure on the duratec, however the gel may be past its prime. mix some up and try.

I have had old gel not kick at all, and I had it turn to a gloppy mess as soon as the MEKP was dropped in

How long will Duratec last on the shelf? Most Duratec products will last six months from date of manufacture under standard conditions (77°F/ 25°C ).

FAQ | Hawkeye Industries

hawkeyeind.com

not sure where you are at, or what shipping would be, however I buy 904 and gel from here as it sounds less expensive than your source:

Duratec, Additive, High Gloss, Clear, 904-001, Gallon Can - 123754

Duratec, Additive, High Gloss, Clear, 904-001, Gallon Can

www.fgci.com

No-Wax: gallon: Gelcoat - Page 1 of 6

Gelcoat

www.fgci.com

 

[76SeaRay]

Thanks for the links. I ordered from Fiberglast as they have pre-colored gelcoat using RAL numbers. Mine comes closest to RAL9010 (white) using a color chart so that would work for me without having to mess with colors. Is it simply a matter of whether it will cure or not? If it is an appearance issue, I could use it on the inside of the V Berth and on the floor as those will likely get covered with carpet anyway.