From here on out, water is the enemy. You want everything well dried when new material goes in. I would not put more water in the hull. Use a broom/dust pan, blower to get any heavy stuff. Then, shop vac. That will leave a little very light dust on the surface. Then, immediately prior to adding material to an area, tack it with a tack cloth. You can buy purpose made tack cloths. Or, use clean cotton rag damp with acetone.
I’ve always used an acetone rag. However, do not get the surface ‘wet’ with acetone. No matter if you’re using polyester, vinyl ester, or epoxy, some of the bond will be mechanical. Especially, if using poly. So, final sand should be with something like 100 or 200 grit paper. Then, vacuum. When you tack it, you want to remove the dust, but, you do NOT want to smooth the face of the surface you’ve just sanded. To much acetone will melt and smooth the surface. At the nearly microscopic level, you want the surface to remain fuzzy. That abraded surface with exposed glass fibers gives an interface that allows a good mechanical bond. If you use a really wet acetone rag, you can easily wipe that fuzziness back off, significantly reducing the subsequent bond strength. (This is somewhat less significant for vinylester and even less for epoxy, but, still true.)
17’ Henry O Hornet w/ Johnson 88 spl
26’ Palmer Scott project hull
14’ Bentz-Craft w/ Yamaha 25
From here on out, water is the enemy. You want everything well dried when new material goes in. I would not put more water in the hull. Use a broom/dust pan, blower to get any heavy stuff. Then, shop vac. That will leave a little very light dust on the surface. Then, immediately prior to adding material to an area, tack it with a tack cloth. You can buy purpose made tack cloths. Or, use clean cotton rag damp with acetone.
I’ve always used an acetone rag. However, do not get the surface ‘wet’ with acetone. No matter if you’re using polyester, vinyl ester, or epoxy, some of the bond will be mechanical. Especially, if using poly. So, final sand should be with something like 100 or 200 grit paper. Then, vacuum. When you tack it, you want to remove the dust, but, you do NOT want to smooth the face of the surface you’ve just sanded. To much acetone will melt and smooth the surface. At the nearly microscopic level, you want the surface to remain fuzzy. That abraded surface with exposed glass fibers gives an interface that allows a good mechanical bond. If you use a really wet acetone rag, you can easily wipe that fuzziness back off, significantly reducing the subsequent bond strength. (This is somewhat less significant for vinylester and even less for epoxy, but, still true.)
17’ Henry O Hornet w/ Johnson 88 spl
26’ Palmer Scott project hull
14’ Bentz-Craft w/ Yamaha 25
PalmerScott- You make a good point. Thanks. I won’t wash it again, but it was seriously dirty. It needed it. I am also fighting the weather. My tent does a great job expect for driving rain…
I will be sanding with a high grit prior to any bonding, so we are on the same page there. I am passed all the intense grinding so it should stay relativ
Well… Im at a cross roads here. I mocked up almost a full size transom to test the vacuum infusion today. But I made some mistakes. This was going to be the last test before I attempted to infuse the glass onto the transom in the boat.
I weighed the glass this time to get my ratios correct. 3 lbs 6 ozs. So I made up 4 lbs of resin. I had plenty of slack in the bagging and it was holding vacuum well.
Here are some things that went wrong.
I made the resin to hot. I went back through it all and I added to much MEKP, not by much but it kicked too fast. I was worried about it pulling the vacuum pulling it dry so I didn’t run it light.
I really needed an extra feed line in the middle of the transom.
I could have dispersed the vacuum line with some spiral tubing.
My mistakes left a dry spot in the center of the mock up. I think the resin would have pulled there just fine if it didn’t kick so fast.
The rest of it looks fantastic! Seriously it did an incredible job.
So back to the cross roads. Do I suck it up and lay everything up by hand? Or do I roll the dice and go for it? I have invested time and money into the bagging, but I really don’t want to rip the transom out again.
Third option. Do the transom by hand and still experiment with bagging the stringers in the mean time. I really do think those will be easier.
I know this makes me a troglodyte, but, I’d go old school. Transom will be a little heavier (maybe a pound or two), but, you’ll be able to be completely sure that all the glass was appropriately wetted out and no voids remain. Yes.
If one was going to be making multiples of some part, you could prototype and test your line layouts and MEK-P rates to make sure the process worked well for the shape and situation you were building. Without that, it seems to me going to bagging introduces opportunity to complicate matters. I know the old school way is a messy, hot, respirator-wearing pain, but, it is simple.
I guess if you were experienced with bagging and were making a very simple part, you wouldn’t need the prototyping and test runs.
Cliff’s Notes - I vote 3rd option. Old school the transom. Play with bagging on later parts.
17’ Henry O Hornet w/ Johnson 88 spl
26’ Palmer Scott project hull
14’ Bentz-Craft w/ Yamaha 25
I AGREE, DONT RISK IT ON THE TRANSOM, GO WITH WHAT YOU KNOW WORKS, AND PLAY WITH THE STRINGERS IF YOU WANT.
YOU MAY EVEN DECIDE TO SKIP THE BAG ON THOSE AS WELL.
EVEN WHEN YOU HAVE TIME AND MONEY INVESTED IN SOMETHING, SOMETIMES YOU JUST HAVE TO CUT YOUR LOSSES AND GET TEH JOB DONE.
I CAN PROMISE YOU, THE REST OF THE HULL WAS NOT VACUUM BAG INFUSED, AND ITS HELD UP THIS LONG, TO THE POINT YOU FELT IT WAS WORTH REBUILDING.
tough call, reality is bagging vs hand layup proabably isn’t going to make a hell of a lot of difference on an old boat, but the satisfaction of successfully pulling off infusing it would be pretty sweet! not to mention not having to mess with a gian wet blanket of resin soaked glass
If you think you’re close in on your process, meh why not? Worst case you have a **** load of grinding time to think about how stupid you were for trying to infuse it
really though, if you have any doubts I wouldn’t risk it, hand layup always works.
I have accepted a new job. I will pretty much out of town for the next two months, at home some weekends and then I will be moving permanently. There wont be much boat building time I am afraid. Luckily I am just moving two hours up the coast (to the dirty Myrtle) so I will still have access to the water.
Now I am torn. I don’t want to move the boat with the floor being in it and that is going to take some time. Especially if I am on the road all the time.
I don’t really want to sell it as I enjoy working on it and want to see the finished product.
I also can’t sell my house with it sitting in the front yard!
Anyway, I just wanted to give y’all an update as I ponder things to come.
Congrats! On the new job.
Hate it that you’re going to Myrtle.
Stick a few cross members in the hull side the trailer back up under her and take her with you. To much success to drop her now.
Or, do the smart thing and give her away.
17’ Henry O Hornet w/ Johnson 88 spl
26’ Palmer Scott project hull
14’ Bentz-Craft w/ Yamaha 25
