Surface Coats

[gcdoyle]

Hi guys, I am really new to the boat building so be patient with me. I'm building a shallow water duck skiff. We have built our plaster mock ups of both the cockpit and the bottom of the boat and have already made a fiberglass mould for both sides. I am using polyester resin and a polyester gel coat and have had problems with it. What kind of gel coat can i use for production boats that is more durable/uv resistant/more user friendly? Thanks alot.

[tunnels]

Originally Posted by gcdoyle

Hi guys, I am really new to the boat building so be patient with me. I'm building a shallow water duck skiff. We have built our plaster mock ups of both the cockpit and the bottom of the boat and have already made a fiberglass mould for both sides. I am using polyester resin and a polyester gel coat and have had problems with it. What kind of gel coat can i use for production boats that is more durable/uv resistant/more user friendly? Thanks alot.

Any kind of gel coat bought from you supplyer should fit the bill of what you are asking !!. What are the problems you been having ?? remember a picture say more tan a thousand words

[gcdoyle]

The gel coat i used had wrinked in some places. I used 2% mekp in the gel coat. And also the gel coat doesnt seem very tuff and was wondering if there is a clear coat or another product i should be using on the outside to make the boat more durable and scratch resistant.

[whitepointer23]

the boat must stay in the mould long enough for the gelcoat to cure properly , exposure to air to early will make it soft and tacky. the wrinkles can be caused by brushing on a second coat which cures faster than the first coat and pulls on it. make sure you use less catalyst in second coat. 2% is not a set ratio. we use 1 to 3 % depending on the ambient temperature. also make sure you are using un waxed resin for lay up. only use waxed for last layer or flowcoat.

[whitepointer23]

gel coat is never rock hard, that is what makes it so easy to polish and repair.

[ondarvr]

When gel coat "wrinkles" it's from it being under cured when another layer is applied, or when the resin (laminate) is applied. There can be several reasons for the under cure though.

When applying resin or another layer of gel coat too soon the styrene will attack the partially cured gel coat and wrinkle

If the gel coat is too thin the cure will be poor and even if it’s been sitting for a long time the resin may still attack it.

If the gel coat was under (or over) catalyzed the cure will be poor and it can result in wrinkles.

[tunnels]

Originally Posted by gcdoyle

The gel coat i used had wrinked in some places. I used 2% mekp in the gel coat. And also the gel coat doesnt seem very tuff and was wondering if there is a clear coat or another product i should be using on the outside to make the boat more durable and scratch resistant.

TWO THINGS THAT CAUSE THE PROBLEMS YOU DISCRIBE !!thin get coatis number one and the most common cause and secondly the first coat of resin needs the catalyst ratio need to be higher then normal So if you work normally at 1% then the first coat need to be 1.5% to go off quickly and seal the gelcoat .Work in smaller areas if its going off quickly but keep the catalyst up !!!
Yes undercure is also a part of the problem so spray in the afternoom and lay up the next day is a good practise to get into . To help even further if you second gelcoat mix 20% of laminating resin with you gel coat and catalyze the second coat at 2% 。 The added resin helps to eliminate the wrinkles .
Good luck .