What are we made of?

[sharsp]

Hi all,
Can anyone confirm the type of GRP used to build our Hollands?

My Holland is my first GRP boat and my knowledge of glass up till now was none existent; I was ignorant to the different types of resins used.
I have some glass repairs required on Omega and was getting close to buying some epoxy to make repairs but was advised that my ship is probably of the polyester resin makeup. If so repairs should be made with this material and not epoxy.

Any hard facts on this topic appreciated.
Cheers

[sharsp]

I have since found out that H25's like 90% of GRP yachts, are made from polyester resin based layups. The net is full of continuing debate about whether polyester resin or epoxy should be used to repair poly boats. Some say epoxy sticks to anything and is better for this that and everything else while others say that poly is cheaper and will happily repair poly boats with minor repairs. I only have small, unused bolt holes and some leaky stanchions to repair so have picked up some poly resin and glass etc to do the job. Haven't had a crack at it yet as I will practice at home first before I dive into the real facelift. not looking forward to it because some of these jobs are just too messy and annoying!

[bigfoot]

Id did my time as a shipwright building glass boats during the hey days of boatbuilding in the 70s and 80s, around the time Doug was building the H25's.

The holland 25's are very well built, I would'nt have one otherwise.

Typically in the 70's hulls were solid glass using polyester resin often fed through a copper gun. Ending up with a very strong layup but somewhat heavy. So balsa and later foam cores where formulated to improve weight.
Late 80's vynilester resins were introduced as a tie layer (1st skin), this was something between an polyester and an epoxy, quite a hard resin to seal and protect from osmosis. This process is still used.
We used epoxy and carbonfibre to build lightweight flyers and up to Maxi's, this system required heating and vacum forming, very expensive but very light and hard, Australia was leading the world in this system, now its common.

Anyway back to the question, polyester is fine for general repairs but Id use epoxy in hard wearing or load bearing repairs, its 100 times stronger but harder to fair.
The type of filler you use is important, depending on the job in hand, get advise as there are many simplfied products available today.

If you ever intend to completely strip the underwater back to glass concider a coat of epoxy primer and your hull will be sealed forever.

The rule is......epoxy over poly is ok, but poly over epoxy doesn't cure.

[appleslice]

Back in late 70s, Apple Slice had some osmosis (no doubt at least partly caused by the warm water mooring in the outlet from Torrens Island power station). I bit the bullet and ground off ALL the gelcoat below about 3 inches above the waterline, and let it dry out in a big shed at Port Adelaide. The hull was then built up using epoxy and solid glass bubbles (not micro-balloons - these were solid glass). After multiple layers of epoxy, several filler coats followed, and a lot of board sanding to produce a fair surface. Several coats of concrete sealer followed, and then undercoat and anti-fouling. A lot of work, but I bet that hull is still good!

[Mystique R333]

Here are details of the hull layup in Polyester Resin from Doug Sharpin's archive. Full document in Old Design Section.

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[pete]

Ahoy there folks - i'm a new member in sunny Mooloolaba.

Yesterday I inspected with a view to purchasing a 1983 built very bare H25 with outboard well, twin spreader rig, great sails, shiny keel bolts, few electronics, lot's of mould, flaky interior paint and areas of FLEXING FORE DECK. The flexing occurs on each side deck adjacent to the forward end of the coach house.

Is there a recommended method of reinforcing the glass where the flexing occurs ?

Regards from Pete