YM senior - hull painting and others

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Posts: 9
Joined: Sun July 19th, 2020, 9:47 pm

YM senior - hull painting and others

Post by Joao »


I am preparing to do maintenance works to the hull of Mikros (YM senior 1967).
Because I bought it last August I am thinking of doing a sort of ''reset'' to the hull finish. I read online that marine plywood has a life expectancy up to 25 years. That is interesting as Mikros has 54 years already. I wonder how many of you that have plywood boats feel about this answers you get from google searching...

Now. This year I tough of sanding all antifoul off and as I don't know how many and different brand/types it has.
Then checking that the substrate is sound and maybe priming it with a hempel two part light primer.
After that, I think hempel requires one coat of under water primer and would use an antifoul from hempels range too.
The topsides I will lightly sand and apply another coat of two part finishing paint (hempel).

As I am set to do this, I thought it might be smart to apply some fibreglass tape to the chines. This could help keep them protected from impact but also ''seal'' the top of the plywood as the two boards abut against another. Does this make sense or will this be bad for the boat in any way?

There is nothing in the boat that suggest failure of any plywood part, quite the contrary. The boat feels really sturdy and you don't see any areas of rot, but I though I could work in preventing and maybe saving the existing hull a many more years.

Kind regards,
Keith Mc
Posts: 18
Joined: Sun August 2nd, 2020, 9:49 pm

Re: YM senior - hull painting and others

Post by Keith Mc »

Hi Joao
A couple of comments from me on what you are proposing. And they are based on personal preferences rather than suggesting that your approach is in anyway incorrect!
Replacing Antifoul: If you are going to the trouble of stripping everything back and plan to keep Mikros for some time you might want to consider Coppercoat. It goes directly onto the Hempels light primer, is a very effective antifoul and is as tough as old boots which is particularly important for a trailer sailer. It doesn't need replacing each year and therefore reduces ongoing maintenance. I have used it on my Golant Ketch launched in 2014 and have used it on my current Senior build. It is however expensive and needs careful application.
Taping the chines: My personal view is that if the boat is well built and sound it shouldn't be necessary. Yes it will add additional protection but I am not sure it is worth the 'downside' of the additional effort required and the visual impact. Others might quite rightly say it doesn't matter a jot! My personal preference is not to see tape lines.
Good luck
Posts: 9
Joined: Sun July 19th, 2020, 9:47 pm

Re: YM senior - hull painting and others

Post by Joao »

Hi Keith,

Your comment is actually very interesting to me. I did have a look at coppercoat and moved await from it as I was not 100% sure of its efficacy plus the application process kind of led me to look for other options. But I think I might just do the coppercoat. I will send them an email this week.

Reg taping the chines, I guess once exposed and see how they are faring, I will decide. I would also rather not have the visual 'unpleasantness' of the tape.

Kind regards,
Posts: 16
Joined: Sun October 25th, 2020, 7:55 pm

Re: YM senior - hull painting and others

Post by Bethem »

Hi Joao,
This is what I did on Bethem.
Chines, primed joints with clear West epoxy, half hour later applied another coat, then used glass tape, coated again and removed all air bubbles, just as it went tacky mixed more epoxy with fairing filler and smoothed over. Once dry sanded and you can’t see any evidence that it’s been taped.
Hull, working with bare wood I applied numerous coats of WR2 two pack solvent epoxy which is a thin coating which penetrates right into the ply and was applied wet on wet. I think I managed 6 coats in a day. Following day it was all lightly sanded and 2 coats two pack epoxy primer, 3 two pack under coats and finally 2 Toplac gloss coats.
Below the waterline instead of the gloss I applied 2 coats of Jotun anti foul.
I am fortunate working in a boatyard where materials are readily available!
Inside the same solvent epoxy was applied to all surfaces, followed by 3 single pack under coats and 2 coats of bilge paint.
Deck. Ply sealed with clear epoxy followed by woven roving cloth, fairing filler, sanded, 2 coats epoxy primer followed by International deck paint.
Cheers Mat
Posts: 25
Joined: Tue September 6th, 2016, 12:07 am

Re: YM senior - hull painting and others

Post by JFJ »

Hi there, good luck with your boat!

I dont have experience with wooden hulls, but Iris (a golden Hind 26) has ply top-sides, and I do have some experience with glassing these for repairs.

You can make fibreglass tape practically invisible for a repair - it flexes really well round curves.

one thing to be careful off is to make sure that the areas are prepped well first - a really good line, as the tape wont hide any nicks worth a damn, and you may end up with voids instead. you might want to skim the chines with a fairing compound of glass balls and silica in epoxy first - really thin. When its tacky, apply 4 inch tape. Remember that with chines you are working upside down for most of the application - be careful of the tape moving or sagging - wet out as little as you can get away with when sticking it up (maybe a bit of silica to slow runs too). Have one of those little metal rollers to ensure you get the air out and to get the glass as close to the hull as possible....

Make sure the tape is for epoxy - not for polyester - there are different binding agents which dont dissolve well in the wrong media. When tacky/dry fair again. You dont have to run really long lengths of tape - work 6 feet or so at a time, or the tape can distort when applying.

As to protecting the hull with coppercoat - that certainly is good stuff, though tedious to apply well (as well as being really expensive). It es also effectively another epoxy sheathing of the whole hull, and may provide additional protection against water ingress into the ply - I couldnt stretch to that this year with Iris - but I did use Jotun epoxy primers to protect my hull against blisters - (3 coats) and it wasnt too hard to apply - though it should be thinned per the datasheets which you can find online.
I had great luck with epoxy coatings on galvanised steel bilgeplates on Iris for years before this process.
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