UK Zip Build

Outboard designs up to 14'

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sproggy
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Location: Welwyn Garden City, UK

Re: UK Zip Build

Postby sproggy » Wed Jun 06, 2018 6:09 am

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?

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BarnacleMike
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Re: UK Zip Build

Postby BarnacleMike » Wed Jun 06, 2018 6:57 am

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.
-Michael

Built Utility "Perseverance" — completed Aug 2016
Currently building a Zip
My Boatbuilding Blog: http://barnaclemikeboats.blogspot.com/
My Website of Boat Photos: https://michaelsmaddox.wordpress.com

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sproggy
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Re: UK Zip Build

Postby sproggy » Wed Jun 06, 2018 7:12 am

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 :roll:

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BarnacleMike
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Re: UK Zip Build

Postby BarnacleMike » Wed Jun 06, 2018 7:48 am

sproggy wrote: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.
-Michael

Built Utility "Perseverance" — completed Aug 2016
Currently building a Zip
My Boatbuilding Blog: http://barnaclemikeboats.blogspot.com/
My Website of Boat Photos: https://michaelsmaddox.wordpress.com

Ayman
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Location: Cairo, Egypt

Re: UK Zip Build

Postby Ayman » Fri Jun 08, 2018 4:23 pm

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?
The Prof

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BarnacleMike
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Re: UK Zip Build

Postby BarnacleMike » Sat Jun 09, 2018 8:44 am

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.
-Michael

Built Utility "Perseverance" — completed Aug 2016
Currently building a Zip
My Boatbuilding Blog: http://barnaclemikeboats.blogspot.com/
My Website of Boat Photos: https://michaelsmaddox.wordpress.com

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mrintense
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Re: UK Zip Build

Postby mrintense » Sat Jun 09, 2018 1:58 pm

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

Crafting a classically styled Vera Cruise named "Some Other Time"

Clipper's Vera Cruise Build

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sproggy
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Re: UK Zip Build

Postby sproggy » Mon Jun 11, 2018 6:51 am

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.

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hoodman
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Re: UK Zip Build

Postby hoodman » Mon Jun 11, 2018 8:30 am

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.

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Jimbob
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Re: UK Zip Build

Postby Jimbob » Mon Jun 11, 2018 9:04 am

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
Jim Neeley
Building a Barrelback in Sacramento, CA
viewtopic.php?f=15&t=28089#p172969

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sproggy
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Re: UK Zip Build

Postby sproggy » Mon Jun 11, 2018 9:21 am

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

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hoodman
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Re: UK Zip Build

Postby hoodman » Mon Jun 11, 2018 9:58 am

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.

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sproggy
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Re: UK Zip Build

Postby sproggy » Mon Jun 11, 2018 2:24 pm

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.


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