UK Zip Build

[sproggy]

My progress on the boat has been frustratingly.......I was going to say slow, but non-existent would be closer. Good news is I've finished building the cycle store so the bicycles are out of the garage and out of my way. I've also completed the transverse bracing on the build form so that's solid as a rock now.

Taking the good advice to encapsulate the frames before mounting them on the frame, I've been rubbing them down to prepare them. Maybe I'm going too far on the finishing for items that will be largely invisible once the boat is complete but boy, am I glad I'm doing them now - it's taking me ages and that's with the ability to turn them over/around. Stem, breasthook and 5 1/2 are now ready - just working on 4 now. What's the usual approach to de-dusting before breaking the epoxy out - just brushing the surface or vacuuming, washing?

[BarnacleMike]

What I do is sand the surface, vacuum it, then wipe it of with a little denatured alcohol. Once the surface has had a few minutes to dry off, I apply a thin coat of epoxy. I repeat this process until I have applied three coats of epoxy.

You have to be sure to let the epoxy cure for 24 hours before wiping it off with denatured alcohol. I learned this the hard way, with both water and denatured alcohol. It interferes with any parts of the epoxy that aren't 100% cured, and creates a real mess.

Another thing to watch out for is amine blush. Some of the less expensive epoxies tend to leave an amine blush after curing. It's mildly greasy to the touch. In the past, I'd simply wash this off with warm water and a mild amount of dish detergent. I've had good luck with System Three Silvertip epoxy not leaving a blush.

[sproggy]

Thanks, Mike. I've often wondered what denatured alcohol, referred to many posts on here, is - we don't have it in the UK. A quick Google search reveals it's what we call 'meths' (methylated spirit). Purple stuff, right?

I'll try it when I'm home but I'd imagine it'll raise the grain of the wood somewhat, or is that not an issue when it's been sanded with something as coarse as 80 grit?

I'm using West System epoxy as it's readily available over here with good support. It is reported to blush after a while but I'm planning my encapsulation work such that I can apply subsequent coats when the previous one is still tacky, thus avoiding the blush between coats. Once encapsulated and fully cured I'll wash the frames with water to get rid of the blush before assembly on the build form. Warning about waiting for full cure noted!

I've been holding off buying a new shop vac (using a broom since the old vac died) in case my wife gets vacuum cleaner envy and steals it for use in the house! But I think it's time to go shopping now. Again

[BarnacleMike]

Thanks, Mike. I've often wondered what denatured alcohol, referred to many posts on here, is - we don't have it in the UK. A quick Google search reveals it's what we call 'meths' (methylated spirit). Purple stuff, right?

I'll try it when I'm home but I'd imagine it'll raise the grain of the wood somewhat, or is that not an issue when it's been sanded with something as coarse as 80 grit?

I can't speak to the purple color... What I'm using is clear. However, methylated spirit sounds right. According to the almighty Wikipedia, it is sometimes dyed. Perhaps that can account for the color / no color?

I haven't had a problem with it raising the grain, at least not on mahogany. I don't use a whole lot of it at a time... just enough on a rag to pick up dust particles & the like.

[Ayman]

Hello
Does anyone know about Bow eye can answer this question. What is the technical difference between using a bronze chrome and stainless steel?
what are the pros and cons?

[BarnacleMike]

Bronze will be much softer than the stainless steel. The stainless steel will be stronger.

Since the bow eye is not a structural part of the hull, I would use stainless steel.

[mrintense]

Chrome plating over bronze is not going to hold up over the long run. Better to go with stainless.

[sproggy]

I feel as if I'm climbing a very steep learning curve. I started to encapsulate my frames on Saturday morning, forgetting the critical advice not to do so when the temperature is rising. I made the problem several times worse by using slow hardener - that just gave the air bubbles more time to form in the epoxy so I spent forever tipping out bubbles as the first couple of coats went off........slowly. By the time I did the final coat the wood was sealed so no more bubbles appeared but I'm not happy with the finish so I'm going to rub the frame down and do a final, thin coat. The ply didn't suffer this problem - it was only the oak.

I started with a 6" foam roller for application and a 2" foam brush for tipping off but the roller sucked up way too much epoxy and, with only small areas to cover, squeezing it back out was messy and it just got absorbed back in. So for subsequent coats I abandoned the roller and used only the foam brush - much better. I expect the roller will be more appropriate on large areas.

The stem and breasthook looked a bit of a mess as I'd somehow raised the grain (possibly too much degreasing spirit) so I rubbed those back down smooth with 80-grit and applied another thin coat and they look pretty reasonable now. I'm happy enough with them and I learned useful techniques on ultimately out-of-sight parts. Wasted a bit of time and epoxy but it's not the end of the world and it has improved my confidence with a process that's new to me.

I'm going to order some fast hardener for the rest of the frame encapsulation - I'll have to do it in the evenings (falling temperature) and slow hardener leaves too long between coats. Now I've got the technique I can work more quickly so fast hardener will be OK, I'm sure. All in, I'm learning and making progress so I'm pretty happy despite some short-term frustrations.

[hoodman]

We've all had the bubbles too and ignored the advice of others! I think sometimes you can get the bubbles just from the epoxy soaking into the wood pores and the air escaping.

[Jimbob]

I got bubbles when I was encapsulating also, especially on the plywood. Usually I just sanded lightly and applied a second coat and everything came out just fine. I have read that heating the wet epoxy with a torch will get rid of bubbles during the cure. I used a heat gun instead sometimes. The epoxy that I used was not flammable.
Jim

[sproggy]

Using a heat gun is a good idea - it should also make the epoxy flow better and potentially give a better finish.

[hoodman]

You're going to have to sand it before putting on your choice of UV top coat whether paint or clear anyways. Unless it will be hidden where the sun don't shine and then you don't need to worry about it too much anyways.

[sproggy]

I figure the breasthook, stem and frame 5 1/2 (which are what I’ve done so far) will never see direct sunlight so the epoxy finish I leave them with will be how they look forever. The finish as it stands is good enough that when I’m head first under the foredeck I won’t wish I’d taken more care.

[sproggy]

Today is the last day of a 3 week sabbatical from work. Not as much boat time as I'd have liked - a combination of family stuff, temperatures over 110 in the garage and getting distracted finishing off the restoration on this:



But I thought I was doing OK:



Anyway, this afternoon I ripped the keel, laid it down over my meticulously aligned frames......and found this gap at the stem:



My first thought was 'shim' but it's actually worse than that. Much worse. It turns out that despite measuring stuff a million times, I've blocked the breasthook/stem about an inch and a half higher than they should be. Obviously my measuring is as accurate as my counting..... Of course I've epoxied the stem, breasthook and frame 5 1/2 together extremely solidly

The best plan I could come up with after drying up the tears is to cut the stem away from frame 5 1/2, scrap it and the breasthook, cut the remains of the stem out of the notch on the frame (much easier said than done) and then start again with a new stem and breasthook. I haven't started that butchery yet - I thought I'd sleep on it - but it would at least give me a second chance at doing the breasthook (which is modified) in a more elegant way.

It's a real shame as I was actually starting to feel that I was making progress. Ah well, you live and learn. The other thing I've learned is that while my setup frame is level side to side and end to end, it isn't actually dead straight. Which explains why the laser alignment beam was telling me one thing and my transverse measurements from the setup members were telling me something completely different. I decided to trust the laser and this was rewarded by the keel dropping straight into the notch on the transom, all frames and being perfectly centered on the stem. Which would be even better if I didn't have to scrap the stem!

[TomB]

Sproggy,

The scooter looks great.

Somewhere in the UK don't they say "a stumble prevents a fall"? I would call this a stumble and not a fall.

If I'm seeing it correctly, frame 5 1/2 is notched and the stem goes through. Could you hand saw both sides of the stem and use a twist to break the frame free without too much damage? Then lower the breast hook an appropriate amount and put things back together? If the breasthook has to be fared or shimmed a little so be it.

Tom