Shearwater 17 fibreglassing

Advice needed.

I have done all the work to get the hull exactly perfect, and I am very happy with the quality so far. However, just about to start fibreglass the hull and not exactly sure how to proceed.

The build book says that I need to overlay 3 sheets of glass over each other and also put a layer of resin on the boat before the fibreglassing.  This does not seem right to me.

The video says to just  put on a layer of fibreglass sheet over the hull and then apply resin.  


I am worried about screwing this up and I have taken 5 months to get to this stage, so I am cautious. I have no help from the local dealer, I have only the forum.

I appreciate your thoughts.


John in Australia

6 replies:

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RE: Shearwater 17 fibreglassing

Hi John,

I assume from your description that you are at the stage to apply the fiberglass and resin to the outside of the hull?  As with anything you can proceed in several ways depending on your preferences.  After trying different ways, I would recommend the following:

1.  Sand hull to round the chines and get a smooth surface (you've probably already done this but just in case......)  Vacuum off sanding dust, wipe with a clean damp cloth (don't use solvents just plain water) and let dry. 

2.  Lay down piece of fiberglass that covers entire hull/chines (wear gloves so you don't contaminate glass with oils from hands and to minimize snagging).  At this point I smooth it all down with a dry chip brush.  Note that you will eventually need to cut the glass so it wraps around the bow and stern, but I wait until I've got the resin on so I can see exactly where to cut. 

3.  Lay down the partial "football-shaped" piece of fiberglass to cover hull bottom as described in manual - American style football, not a soccer ball shape here! 

4.  If you want to do additional layers or a keel strip, add it on top of the football.  Always put the larges piece on the bottom, smaller on top so that you don't need to worry about sanding through weave on full size piece of cloth when you smooth seams later. 

5.  Smooth all glass layers down with dry chip brush.

6.  Mix resin and apply.  I usually start in the middle and work towards the ends so any excess cloth can get taken care of at the ends without wrinkles in the middle.  Be sure to totally saturate cloth (takes a minute with 2-3 layers) and squeegee well to minimize weight and get a close glass/wood contact. 

7.  After resin is cured to at least tacky stage, apply fill coats (if you wait too long you have to sand between coats - more work!)

I searched through many build blogs to see what everyone did - and keep asking questions here.  You'll do great.  Just remember that no matter how bad you mess up you can always fix it and no one will notice in the end (speaking from experience). 

RE: Shearwater 17 fibreglassing

Thanks KathyD, you sound like you know what you are doing. Step 1 is done and looks good. I  understand steps 2-5. 

Step 6 is new. I have not used a squeegee before, I used a brush when I glassed the interior. I assume it is like he video, mix a batch, pour it on the hull a fan it downward letting he cloth soak up the resin.  There may be three layers of cloth and i would hope they dont move when squeegeing the resin in (logically, i would have thought one layer at a time, then resin in, then more layers repeating the process). Seems like this will need a lot of resin. This step seems to be one that can go badly, as i had to do a lot of sanding when I did the interior (lots of bubbling, sanding, resanding). 

Step 7 is also a bit strange. I assumed once you did step 6 it was done, as per video and manual. What is a fill coat?

A bit frustrated at the lack of details in he manual, and also how there are such differences between the manual and video, but I guess thre are many ways to do these things.

RE: Shearwater 17 fibreglassing

6.  To minimize the cloth moving around, put a weight on it in the center and then remove the weight once some of the resin has been applied.

7.  There's a really good section on filling the weave in the Tips for Boatbuilders section on this website.  Look for it under the heading Working with Fiberglass.  Much better description of the process than I can provide.   

RE: Shearwater 17 fibreglassing

I have finally done the first coat just now.  I started with the football piece on top of the main piece of fibreglass cloth, but quickly got rid of the extra piece as it was just not working well.  The extra cloth was moving all over the place and I did not think i could mix enough epoxy in time to do the lot, and also without significant bubbling.  Anyway, i made a call to get rid of the extra piece and just do as the video described, which is one layer of cloth.


So i ended up coating just the one overall piece of cloth, and it seems great so far.  I will follow up with a fill coat in the morning (after 12 hours) and do not plan to sand at this time.


With this outcome, is this ok?  Can i put more cloth on this in a later stage?  Does it matter?


thanks in advance for any advice.



RE: Shearwater 17 fibreglassing

Just another update. I have put a few more fill coats on now, with some sanding in between. Will keep doing this till the weave is full. Is it possible/recommended/dumb to put another piece of cloth on after filling the weave?

RE: Shearwater 17 fibreglassing

I think you will be making a lot of extra work for yourself, with little benefit.  You'll have to start the whole weave filling process all over again on another piece of cloth, and I don't believe it is structurally necessary.  Once you have about two or three fill coats on the cloth, start sanding in earnest and go for a totally smooth surface.  You may have to do another coat or two to attain that, but it shouldn't be necessary to add another layer of cloth.  Read the section on working with fiberglass in the Tips for Boatbuilders section listed at the top of this page for a well detailed description of the process.

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