Thursday, September 11, 2014

The Bow is Back

I know I said I wasn't going to do this, but...  I changed my mind...

After speaking with a friend about the bow, he guilted...  I mean, talked... me into making a better long term decision.  While I really didn't want to do this project, I know it's the right thing to do given that this boat will be bashing through Lake Ontario weather on a regular basis.

So, I whipped out my trusted Harbor Freight oscillating tool and made some incisions.  I used a small pry-bar and a hammer to gently tap and pry the top laminate and inner foam out.  It's a good thing my friend talked some sense into me, because the area I thought was about 16" back from the bow turned out to be the entire bow from the tip to the mast compression post.  Much worse than I'd hoped.

The foam was not properly laminated, and had split in many places.  A prior owner had "repaired" this by injecting copious amounts of resin throughout the bow.  They had also laminated nearly 3/16" of resin on the top of it all in some places.  By the time I removed all the foam, I was left with some significant resin pools that had to be removed with an angle grinder and 60 grit disc.  That was no fun inside the tight quarters of that bow.

Eventually I cleaned it all out, removed the dust and took measurements.  I then ordered one large sheet of 1/2" Divinycell foam from Jamestown Distributors, which is enough to do the entire bow if opposing triangles are cut properly.

I did some minor fairing using epoxy thickened with colloidal silica prior to laying up the foam.  I didn't want any significant gaps if it could be avoided.  While colloidal silica is a bear to sand, it's very strong, so makes a good foundation.  With careful use of the spreader I was able to minimize my final sanding efforts.  After a wash down to remove blush final sanding was completed with a 6" RO sander that has nice dust collection ability.  The 60-grit disc should provide plenty of tooth for adhesion to the foam.

Last step was to wet out the bow and foam with neat epoxy and a spreader, then mix up a pretty significant batch of epoxy thickened with colloidal silica.  I actually did this in about 6 batches because it was a hot day and I didn't want it to kick off too early.  Each batch was spread out with a notched spreader for even distribution until the whole area was covered.  I carefully put the new core in place, and pushed down on it to set in place.  The last step was laying some scrap wood battens into place to distribute the load, and then laying some sand bags on top to ensure proper form.

Next steps will be to inject thickened epoxy into any remaining voids between the foam and the existing border, and fair that transition.  Once the transition looks good, I will apply the top laminate of 2 layers of 6oz. fiberglass cloth throughout.  That should conclude the bow core repairs...  Stay tuned!