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sea nymph gullwing floor / stringer replacement

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    Posted: 30 May 2017 at 11:01am
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I bought a 5m sea nymph gullwing as a project, I know that it has a rotten floor and stringer problems. Ive seen pictures of the strings under the floor. I wondered whether anyone here has experience of them. Are those strings hollow fibreglass or wood cored ?

I know mine are cracked so I was thinking of replacing them with a glassed marine ply frame. Thoughts ?
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Post Options Post Options   Likes (0) Likes(0)   Quote MikeAqua Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2017 at 11:35am
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Instead of ply - you use a synthetic core and not have to worry about rot ever again? 

If you can track some down in NZ ...

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Old boats that have had treated marine ply used as transoms/ keels/ stringers tend still to be very solid today.. unfortunately not all unused treated timber formers.. and not all had quality ppl laying up...

 Hollow glass is very hard to lay up...not industry practice.. and as you seem to have grasped, in many applications it is the shape of the glass form that gives the stiffness in a single direction to a panel rather than what it is formed over like as in corrugated iron and corrugated cardboard... Hence in many applications.. non boat stuff, a rolled paper.. similar to toilet tissues was used, or cut strips of urethane foam.

 Come to a boat hull, I would stick to marine treated ply, preferbly pre sealed/ coated for stringers etc.
We used to cut/ shape, radius the top cnrs (other wise the glass will not lay down well) fix to the panel...then a wet stray of resin to seal, then hit with the chopper gun and roll out.


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Post Options Post Options   Likes (0) Likes(0)   Quote mikejf Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2017 at 1:48pm
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Yes I was thinking about that, I want to check the transom at the same time but it seems sound. Ive seem many options on youtube but I wasnt sure what would be available in NZ. I will go with ply if I can find nothing else. My boat is a 1979 so if I get ten years out of a floor rebuilt with ply I will be happy.
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Post Options Post Options   Likes (0) Likes(0)   Quote mikejf Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2017 at 1:51pm
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Steps would you advise polyester resin or epoxy ?

Also, I see that the Americans on youtube make up a mixture called "peanut butter" from resin, cabosil and fibres to bed in stringers. Do people do the same thing here ?
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Post Options Post Options   Likes (0) Likes(0)   Quote MikeAqua Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2017 at 4:05pm
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Cabosil thickens resin to make it viscous so it can be used like a glue.  It's a very strong adhesive once cured. 

That's what we used in my regeant for fixing new stringers and adding bulkheads.

You can also buy tubes of pre-thickened resin.  Just be careful not to breath the dry cabosil in.

We didn't bother with marine or BS-1088 rated ply. 

We used B/C grade treated ply and filled and hot coated then installed before the coating had cured.

One tip - don't forget your drainage holes Embarrassed difficult to drill once a panel is glued in.



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I've done many of the v146 boats. If you require any advise or pictures of floor and transom replacement phone me on my cellphone on my profile. .....😃
Last week I joined an Anti-Social support group........We hav'nt Met yet!

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Peter (above ) is far more  up to date than myself on the technology.. mine goes back to the 1980s when I owned a fibreglass manufacturing company..a little marine, mostly industrial / transport stuff.
 So I do stand to be corrected here and there.

I want to check the transom at the same time but it seems sound.

Transoms tend to 'rot' from the bottom.. where the bung is.. god solid tapping with the handle of a large screwdriver....should be a solid sound from top edges right to centre and base.. and no soft patches.. If still in doubt pull any fittings, the motor and check inside those holes...in some instances you can drill some mounting holes slightly larger and replace with slightly larger mounting bolts... ladders, tabs , speedo pick ups etc.


I will go with ply if I can find nothing else.
 I do suggest to go marine ply, lay the laminates in the vertical position to take advantage its strength in that direction...means a little shaping to the hull

Steps would you advise polyester resin or epoxy
?

 Its a matter of cost/ preference and long term considerations.
 Epoxy is stronger than poly... its a a small boat and the poly to date is doing quite well on your an many other boats..
Epoxy is more expensive
Epoxy can me put over poly, but poly doesnt  'stick' as well to epoxy.. consider this to future applications of say spraying gelcoat finish.
I take the long term view..like restoring a vintage British car and replacing original nuts and bolts with metric.. at least some unc/ unf threads can interchange with a quick tap or dye.. but mix with metric.. that a future headache .. you dont know what is what and where....
 
 The use of fillers... talc , aersils etc...than more for use to thicken and hold up, castings and things like that... eg car bog  in simplistic terms is poly or epoxy with a lot of filler added.
 I strongly suggest to kit yourself out well...not just brushes, but a couple rollers as well...much of the strength is is in the right ratios by weight of resin to glass fibre.. from memory we used to weight off the glass rovings and resin off scales at 1/2 rovings to 2/3 mixed resin... laying out.. getting the air our with a brush has one tending towards a resin rich mix... rollers faster, and far more efficient.

The keel.. check that.. pull the brass strip.. screws that the thread is soft gone.. cant torque up...a drill up inside a few of the holes will show a lot... if looks ok.. drill the screw holes out slightly..make up some small dowel plugs... you can mix up expoy, and pump up into the holes, then wack the plugs into the holes. Then just re drill new screw holes.
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Post Options Post Options   Likes (0) Likes(0)   Quote pjc Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2017 at 6:42pm
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Originally posted by Betty Boop Betty Boop wrote:

I've done many of the v146 boats. If you require any advise or pictures of floor and transom replacement phone me on my cellphone on my profile. .....😃
west system unidirectionall cloth +good quality marine ply?pre coat ply with evadure?


going fishing tomorrow but tomorrow never seems to come.
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I prefer to keep quiet and watch all of the expert supplied opinions ....no bodys   even mentioned the health'n saftey aspect of this job......
Last week I joined an Anti-Social support group........We hav'nt Met yet!

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Originally posted by Betty Boop Betty Boop wrote:

I prefer to keep quiet and watch all of the expert supplied opinions ....no bodys   even mentioned the health'n saftey aspect of this job......
Ha ha correct on H n S better to take a boat shop
going fishing tomorrow but tomorrow never seems to come.
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Post Options Post Options   Likes (0) Likes(0)   Quote Polar_Kiwis Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2017 at 10:23pm
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Give it a go yourself. Mask for not breathing in fibreglass dust. Gloves when using epoxy and acetone/esol

I would use epoxy and then paint. "Don't let anyone tell you epoxy and glass is hard". That's the advice I was given. "Mix it up in the right ratios and slap it on."

Your boat will be a great project.

Checkout this book:
http://www.westsystem.com.au/files/fibreglass_boat_repair__maintenance/rm_fiberglass_boat_repair_and_maintenance.pdfbook
Here fishy, fishy fishy.... Nom, nom, nom
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Post Options Post Options   Likes (0) Likes(0)   Quote MikeAqua Quote  Post ReplyReply Direct Link To This Post Posted: 31 May 2017 at 8:47am
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Originally posted by Betty Boop Betty Boop wrote:

no bodys   even mentioned the health'n saftey aspect of this job......


There are no health and safety laws for DIY LOL

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When you buy the cans of stuff read the bloody instructions.. including handling, cleaning equipment etc...
The only one that maybe missing is with the sheet of marine ply...when cutting not the best idea to breath the dust.
When using tools, scissors, stirring sticks , disk sanders etc...I assume that those instructions that came with them have been read also.

Maybe the only thing not in instructions is if mix up a spaghetti tin of resin, and dont use it all... leave it out in the open away from everything.. it can get very hot and cause a fire.

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Post Options Post Options   Likes (0) Likes(0)   Quote MikeAqua Quote  Post ReplyReply Direct Link To This Post Posted: 31 May 2017 at 9:48am
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Always a good idea not to breath in dust from cutting, grinding, sanding etc. 

Even wood shavings from some timbers in their natural state can cause things like nasal cancer.

Silicon dust (e.g. cabosil) you do not want in your lungs.

A good respirator with replaceable cartridges (dust/vapour) isn't that expensive.

Hooking a decent vac up to your sander is a good idea too.  Google will show you how to make a simple dust catcher out of a plastic bucket
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Post Options Post Options   Likes (0) Likes(0)   Quote mikejf Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 2017 at 12:04pm
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Thanks for all then advice guys, its much appreciated.

I found that the boat and trailer didnt fit through my side gates into my garden. ( Too wide. ) So my first project has been to pull my fence and gates down and build wider gates.

The posts are 2m + macracarpa logs ( 20x10 cm ) so its proving heavy work. But once thats done in the next few weeks I can move the boat into position and start the work.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 2017 at 3:49pm
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I am no expert, but since I am planning to build a boat I have done a heck of a lot of reading.

I would use marine ply laminated with thickened epoxy. Tabbed to the floor with two layers of 400g biaxial. Everything covered with epoxy to insure it is protected from water etc.


Abrade the hull where the stringer is to go in then make sure that there is a good bead of thickened epoxy between stringer and the hull and the stringer sits on this evenly.  That will help to reduce hardspots where there is uneven loading of the stringer onto the hull. Fillet with epoxy thickened to peanut butter consistency, and 150mm 400g fibreglass biaxial tape over that after it firms up some, but before it fully cures. Offset the layers of tape by 50mm to give a smoother transistion.

Add cleats/frames  to get a good bonding surface and reinforcement then epoxy glue over that. Precoat the underside of the sole (assuming marine ply?) with two layers of neat epoxy and then lay it in. 

If you need to let the epoxy fully cure between steps then you will need to wash any amine blush off with water (use soap but NO solvent) and a scrubbing pad. Dry with paper towels. 

I have the plans to build a boat of similar dimensions to the SeaNymph and that's the layup method used in a nutshell. 


The bateau website has many examples of a boat being built from scratch. 

I have linked to the bit where they install the stringers here. This particular boat is a bit lighter than yours so I would beef things up a little but follow the same process. 



If you browse that site they also have a rebuild and repair thread. Plenty of experienced advice from people who have built boats, and the site owner is a qualified marine architect. 



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Post Options Post Options   Likes (0) Likes(0)   Quote Schampy Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 2017 at 7:11pm
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Also have a look at the Bowdige Marine Designs website. There are dozens of boats at different stage of construction. All ply / glass. It really isnt that hard to repair a couple of stringers and glass in a new floor. Tons of info on the web....
Use marine ply. I would rate West Systems  as the best epoxy ... mainly because of the number of additives they sell to make glue, filler, fairing compound ect....its all just added to their 5:1 epoxy resin. 
Its just a case of getting stuck in and dealing to it.
have fun 
Lance.



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Post Options Post Options   Likes (0) Likes(0)   Quote kishidabu Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jun 2017 at 8:08am
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About those stringers:  I am redoing my deck right now and the stringers (which are glass and hollow) seem to have a really thin layer of chopped strand over them but it is spotty.  It looked like the deck had never been replaced so I am assuming this is the original   Can anyone comment on this?  Should there be a layer of glass going over each stringer tying it to the bottom of the stringers?
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Post Options Post Options   Likes (0) Likes(0)   Quote kishidabu Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jun 2017 at 8:27am
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While we are on the subject of Sea Nymphs can anyone tell me or show pictures of what these stainless steel clips were supposed to be used for?  I am assuming some kind of mounting for a screen???  Thanks!
 
 
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