MERLIN ROCKET FORUM

Topic : High tank

Given the comments on the site about lack of stiffness with a high tank and the problems of shroud tension.
Can you, should you convert a high tank to a low tank and stiffen the hull on a Smokers Satisfaction? I have just purchased a SS with a high tank.


Posted: 15/02/2006 11:49:40
By: Jonathan
Probably not, unless you intend to deck step. The stiffness primarily is needed to cope with the shroud tension needed with a deck stepped mast. However, if you are going to modify your SS a certain amount of logic would have said that you should have purchased a newer or an already modified boat, unless of course you have time on your hands and enjoy tinkering with woodwork.

See the how to guides in the library on this site for further thoughts. Although not in the one in the link bellow there is also one on swaping the transom shape on an SS.

http://www.merlinrocket.co.uk/library/how_to/tuning_older_boats.htm

Posted: 15/02/2006 12:01:42
By: Alan F
Thanks, I purchased it because it was there and I am one of those sad people that enjoy the woodwork as much as the sailing. Modern designs and my 18 stone seem to point to singlehanded. I would like to update it to take a modern rig.


Posted: 15/02/2006 16:48:13
By: Jonathan
Jonathon,
Having acquired an old SS last year, here, for what it's worth is a quick summary of what I did to her.
Carbon sheathed the decks (old deck finish was beyond economic redemption). Fitted carbon struts between hog/chainplates/mastgate. Reglued loose inwhales, dryed out and reglued damp hog/keelson, reglued thwart/c/b case joint (waving in the breeze!)
Refitted full width traveller.
Hog stepped rig retained.
Repainted hull.
Boat is now seriously stiffer. Having sailed old unmodified smokers before, the sidedeck now lifts instantly beneath you when a gust hits, instead of waitng for a several seconds before all the slop in the system is taken up!


Posted: 15/02/2006 16:59:25
By: BmaxRog
BMaxRog - we need to see some photos of this strut arrangement!


Posted: 15/02/2006 17:29:39
By: Mags
Roger - can take some snaps next weekend if you like?


Posted: 15/02/2006 19:16:36
By: Jon
Also, having seen the carbon sheathing and been impressed, I'd like to know who to do it, no having any experience with carbon!


Posted: 16/02/2006 06:59:22
By: Alan F
Ahem, here goes-
The rationale for carbon sheathing the deck worked something like this: The decks were pretty poor-not b- awful, but even serious amounts of graft would only restore them to so-so condition, and the next exposure to the weather would put you right back to square 1. Re-decking was an option but, whilst looking good, requires lots of skill, time etc. and the at the end you're no better off than option 1 above.
Carbon sheathing seemed a reasonable bet, Advantages seemed to be it was achievable without monster amounts of skill, there was a big gain in terms of weatherproofing, stiffness and looks, although a down in terms of extra weight-but let's face it, she's a 25 year old boat, how many ST events is she ever going to win nowadays? Far better to try and keep her sailing for the future of the class, and keep the wet out of her.
Doing it proved to be a steep learning curve, but also a lot of fun. It's not perfect, as Jon will tell you, but one or two small blisters are on low load bits of the foredeck. I'm actually quite proud of the sidedecks! Main reason for the voids was iffy lighting in the barn where I was doing the job-I didn't see 'em!
A big advantage to using carbon is you can add more and more strength where you want it. Panatella had the classic problem of cracking on the deck around the shrouds, so I've put three or four layers of fabric around here. This was also the problem which led to the struts. You can buy carbon tube over the internet, there's quite a few suppliers, but I'll admit I used the quick and dirty solution. This was to get(quiet muttering into coat collar here)6 ash broom handles (yes, honestly!)from local farmers warehouse (cost about £10) and then laminated unidirectional carbon onto them, then flow coat. then cut to size. They are laminated in to form a triangulation, one strut from hog at mast step to chainplate, one from chainplate to the deck beam next to the mastgate, under the foredeck, one from just forrard of mastgate down to the hog.
Doing the sheathing, very broadly is:-
Strip the decks to bare wood. As you aren't interested in preserving a pretty pretty finish this is welll easy. Use a belt sander, seriously coarse grade and get stuck in! i guarantee even two-pot will come loose in seconds!
Squeegee (NOT brush or roller!!!) neat epoxy mix all over the deck (mask off every thing else in sight, please!). Allow to dry for about a day, but not to go fully off. Squeegee on more epoxy, and then lay on cloth. Use clamps all round gunnels etc. to hold in place. Allow to go off for about an hour or so, so the epoxy is starting to really grip the carbon. Then squeegee on more epoxy, to full wet out the carbon (use good lighting!). Allow to go off for a day or so, then two-pot varnish the decks-several coats.
Easy!
There's quite a bit more of course, but if anyone's seriously contemplating doing something similair, I'll happily spout forth more.
cheers
Rog


Posted: 16/02/2006 09:39:34
By: BmaxRog
So the choice of carbon had nothing to do with your mate Pat having shiny carbon decks on his yot then?


Posted: 16/02/2006 11:35:37
By: Jon
Oh yes, forgot that.........


Posted: 16/02/2006 12:08:39
By: BmaxRog
can anyone recommend any carbon suppliers?


Posted: 16/02/2006 13:52:01
By: john
Yup.

http://www.cfsnet.co.uk

Posted: 16/02/2006 14:18:38
By: BmaxRog
So you didn't have to apply any compression to the deck sheeting, just gravity?


Posted: 16/02/2006 15:54:21
By: Alan F
Oddly, no, the finish seems to be pretty acceptable with out. For the true pro look of course, it's probably a must have, but pulling down a vacuum on that sort of area is going to require pro equipment, and, needless to say, pro costs! e.g. Vacuum pump and ancilliaries ca. £500. I got around it on the struts by using tape wound tight over the laminate. The main priority is to avoid excessive wetting out, hence use the squeegees, which are far better at spreading out resin correctly. Brushes are a no-no. Also, epoxy the surface 24 hours before putting on the cloth, prevents resin starvation, Then epoxy just before you lay the cloth on, stops it sliding about as you try to wet it out, and means it's being fed resin from both beneath, and on top when you apply the final resin. 
Don't be tempted to flow coat it with epoxy to make it look nice and shiny, that adds way too much weight. Use two pack varnish for that. The two pack will cover itself with little bubbles, get rid of them by lightly rolling with a good quality mohair roller.


Posted: 17/02/2006 09:01:07
By: BmaxRog
Bob Hoare did well years ago with PVC sheet and a vacuum cleaner for his Cold Moulded FD's.


Posted: 17/02/2006 11:08:14
By: Ancient Geek
Main problem with trying to vac down the deck is not so much getting something to suck(OOhh nurse!) but sealing all the likely leaks, especially on an awkward shape (like a deck thats still attached to it's hull) AND pulling enough vacuum to make it worth while- a nice empty vac bag might make you feel proud, but is it actually doing anything?
Old fridge motors apparently make good vac pumps, but you need to get hold of tubing that won't collapse.


Posted: 17/02/2006 11:48:38
By: BmaxRog
old compressor in reverse, using a beer barrel as a vacuum reservoir!

(empty the barrel first!)


Posted: 17/02/2006 14:33:19
By: john
...and it's the atmosphere what does the pushing, not the vacuum doing the pulling


Posted: 17/02/2006 14:34:39
By: john
I know that! The atmosphere is also very anxious indeed to fill the vaccuum in, as you'll find out if you try to create one without sealing it tighter than a duck's chuff. "Pulling the vacuum" is what's known in this country as a "figure of speech".
Running vacuum cleaners, fridge pumps etc etc for long periods (like the hours that epoxy takes to go off) is not a really great idea anyway. Running them in an enclosed space with epoxy, thinners, paint and flammable wooden boats is an even less great idea. If you care to try it, feel free. If you get better results than me, well bully for you.


Posted: 17/02/2006 15:23:21
By: BmaxRog
BmaxRog,

Any chance of you posting some pictures of the finished product? All sounds very interesting.

Thanks

RichardB


Posted: 17/02/2006 16:55:21
By: Richard Battey
yes, any pictures?


Posted: 17/02/2006 18:41:29
By: Miles
Lets see some pics, should John Howard Be affraid ?? I dont think he is keen on the old Carbon, could put him out of business


Posted: 17/02/2006 18:45:30
By: RussHopkins3374
Top tip,  run the exhaust of the vacuum pump out into the open air becuase the oil which it will pump into the air (in your shed) will pretty well s**t up (read fish-eye) anything you paint inside your shed for a long time to come.


Posted: 17/02/2006 20:54:45
By: Jon
I used to vac bag rudders for model gliders. I used a fridge compressor with a vacuum advance of a mini attached to a threaded rod with a spring. I adjusted the tension on the spring and could get anything from 0 to almost 1 Bar. It only runs to hold the vacuum so 5 seconds every 2 minutes or so. I can e-mail photos if anybody interested.


Posted: 17/02/2006 22:11:42
By: Nigel3280
Didn't realise my project would be this popular!
Jon-did you take any pics at the weekend? I haven't got the technology to do them myself. I might be able to get down this weekend (Sunday) to assist if you haven't done so yet (and you can be arsed to do so.....)
Russ-it'll be a long while before I could hope to match John Howards skill level at boatbuilding-if I could, I'd have built one from scratch! By the way, I'm not sure John is that uncomfortable with carbon, 'cos Lawrie Smart is, and he's also a boatbuilder, and looks just like John Howard, so the question is:- Have they ever been seen in the same room at the same time? I think the public should be told........
Vac bags-just be aware that from the reading I've done, the bigger the area you're dealing with, the more sophisticated the kit has to be. Doing small areas is relatively easy, but not a whole deck. There must be NO leaks-think about that for a moment, with regard to a scruffy old deck, peppered with old fitting holes, splits, cracks, shakes, porous old ply etc etc, AND the fact you'll only find that you've got a leak when you've layed everthing in place. This will leave you frantically trying to find that tiny little leak hidden er, where? Before everthing goes off hard.


Posted: 20/02/2006 10:33:58
By: BmaxRog
correct, Bmax - one off bag presses are a nightmare, once you're mixed up there is no time to mess about - it takes lots of practise to make it work, dry runs etc!


Posted: 20/02/2006 10:42:18
By: john
Thanks for the reply. Can I it take that the tank is left alone as no one in this chain has suggested otherwise and that the best option is to stiffen the shroud/hog/mastgate triangle?
I would like to leave the deck as only one eighteen inch section on the starboard quarter is damaged. I have redecked dinghies in the past and the finished look is worth the effort.
P.S. The sail number is 3075.


Posted: 20/02/2006 16:08:11
By: Jonathan
good question. does one add spaceframe and mast support etc without low tank conversion, or should they both be done together? or will low long tank plus mast support add enough stiffness without spaceframe?


Posted: 20/02/2006 18:28:06
By: john
Rog my Merlin is going o johns For a revamp soon would of done it my self if my garrage ws wide enough, would recomendhim to anyone in the Glos/worcs area, you should of seen the job he did on my Phantom, made a silk perse out of a sows ear.


Posted: 20/02/2006 18:36:41
By: RussHopkins3374
Jonathon,
If you're not going to redeck, I'd leave the tank alone. Replacing it is really only practical if you're going for the full monty, deck off rebuild. Trying to do it with the deck still on doesn't bear thinking about!


Posted: 21/02/2006 11:37:19
By: BmaxRog

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