Shearwater 16 hybrid - Glassing the hull

I was curious to hear opinions about how to glass the exterior of the hull for a Shearwater 16 hybrid.

This boat uses 4 oz. cloth (I think?) in three layers. First layer covers the the entire hull. Second layer covers the bottom panels, overlapping the chine onto the lower side panels. Then there are thin strips that run along the keel from bow  to 4 feet back, and similarly from the stern.

 I'd be inclined to wet out each layer separately. I recall that in class at CLC, it was possible to lay dry cloth over a layer very soon after it had been wetted out. I'm guessing that the second layer could be rolled out, cut and wetted an hour or two after the first layer had been wetted out? Then similary for the strips on the bow and stern, though I might be inclined to do those the next day.

 I've also seen build logs that look like all the glass was layed out, and then wetted out in one swell foop. Seems risky to me. 

Another way to do it would be to wait a day between layers. Would it be necessary to do a light sanding before laying the next layer if done this way?

 What seems like the best schedule to use for this step? How long would you wait before laying the different layers?

6 replies:

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RE: Shearwater 16 hybrid - Glassing the hull

Doing all 3 layers at once is the fastest way, but it needs a pretty good experience level to succeed. Even if you do get everything on properly, it has the highest potential for excessive epoxy use and weight gain. I've done it, but only for work where speed was much more important than epoxy conservation and performance (like the hatch cover for a 28-ft cabin cruiser).

Doing the layers separately gives you much better control. The minimum wait time should be until the previous layer is no longer tacky. Otherwise it could snag threads from the next layer.

The maximum wait time without sanding depends on the brand of epoxy. With System 3 Silvertip, 1 day is definitely not a problem. I've actually gone a week between layers without sanding. It's great stuff - no blush, very viscous with good wetting action. It's the best laminating epoxy I've used. I definitely recommend the slow hardener.

This time of year in the northern hemisphere, I like to do a layup first thing in the morning with the shop still cool from the night, then give it all day in the increasing heat to cure, then do the next layer the next morning. If you're in a hurry, you can probably put on a layer in the morning and evening.

Good luck,



RE: Shearwater 16 hybrid - Glassing the hull

I did mine all at once. 

I would not recommmend doing it separately. The main advantage to doing it at once is you can slide the sheets around before you start epoxy to get everything lined up exactly the way you want.

Just be careful not to press to hard around the cut edges of glass as this will minimize pulling the threads and making a bit of a mess. 

RE: Shearwater 16 hybrid - Glassing the hull

Dear Fishbuster.... I finished my Shearwater 17 Hyrid this spring and did it the slow way.... one layer at a time, with a day or two in between.  I used the Silver Tip epoxy, but still lightly sanded between layers.  I even put a sealer coat of expoxy on the open wood first.  This gave me very good control over each layer, but may have added some extra epoxy weightl  Plus they say the chemical bonding is not as good between layers if you wait too long..... but it's clear, smooth, and solid.  No floating or air bubbles.  It worked for me;  I had plenty of time, and a little more weight was not a concern.  Good luck!  

RE: Shearwater 16 hybrid - Glassing the hull

Well, I got the hull sanded down and ready for glass. Fiddling with some rice paper paintings to place on the bow side panels but should be ready to go tomorrow evening perhaps.

 The rather vaguely worded manual does mention, "Plan to do it in one session." (page 33)

 But Fishbuster, I'm not sure I am as brave as you:) I am flying solo here and have limited experience getting this much glass wetted out. I'm thinking it would be safer for me to go one layer at a time. Perhaps if I can get the big piece on in the evening, I could run the smaller piece over the bottom panels early the next morning, then tack on the bow and stern strips the second evening. That would be perhaps 9-12 hours between layers?

 I'm using the MAS low viscosity resin and slow hardener that ships with the kit.

I'm not in any hurry, just trying to stay out of trouble as much as possible.

RE: Shearwater 16 hybrid - Glassing the hull

Do it the way you are most comfortable doing it.

Neither way is wrong.

I tried to follow along with the book as much as possible.

I had no previous experience, it was my first build and didn't have any problems with the glassing.

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