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What happened to Zenyatta - Gunboat 62

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What happened to Zenyatta; apparently they are in the middle of a big refit , "...peeling a bunch of the bottom...", "...drying out core..."

 

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Nothing "happened". Kerfed core on a wet layup boat that was 15 years old. The core was wet. 

 

The owner decided to do a refit. 

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15 minutes ago, soma said:

Nothing "happened". Kerfed core on a wet layup boat that was 15 years old. The core was wet. 

 

The owner decided to do a refit. 

How did the core get wet?  It sounds like an extremely extensive "refit" for a boat that isn't that old.

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15 years isn't old? Solar panels are about twice the efficiency as then. The old school electrical systems are obsolete (and heavy). The engines had loads of hours. The original daggerboard design wasn't fast. The winches were S-L-O-W. No one likes the split bridle mai sheet system. The paint was 8 yrs old. The SeaDek was 8 yrs old. If anything, she was overdue for a refit! 

As for the core, any kerfed core/wet layup boat will (eventually) get a wet core. From where? Everywhere/anywhere. Sail drives, thruhulls, leaking integral tanks, deck fittings, screw holes in the bilge that allow water bilge water out, rudder bearings. You do your best to make everything waterproof, but there are lots of likely culprits. 

 

Nothing suprising in the need for a reft. One a decade seems appropriate to me. It's a great boat and will be far better afterwards.   

 

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Is that kerfed-core based on wood - or other organic materials? ... isnt quite ordinary that a 15years old expensive cat need a rebuild of the bottom hulls - given normal maintenance?

If used vacum for layup - would that last longer?

    

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34 minutes ago, soma said:

15 years isn't old? Solar panels are about twice the efficiency as then. The old school electrical systems are obsolete (and heavy). The engines had loads of hours. The original daggerboard design wasn't fast. The winches were S-L-O-W. No one likes the split bridle mai sheet system. The paint was 8 yrs old. The SeaDek was 8 yrs old. If anything, she was overdue for a refit! 

As for the core, any kerfed core/wet layup boat will (eventually) get a wet core. From where? Everywhere/anywhere. Sail drives, thruhulls, leaking integral tanks, deck fittings, screw holes in the bilge that allow water bilge water out, rudder bearings. You do your best to make everything waterproof, but there are lots of likely culprits. 

 

Nothing suprising in the need for a reft. One a decade seems appropriate to me. It's a great boat and will be far better afterwards.   

 

What portion of the boats original price would it cost to do the type of refit described here?

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1 hour ago, SeaGul said:

Is that kerfed-core based on wood - or other organic materials? ... isnt quite ordinary that a 15years old expensive cat need a rebuild of the bottom hulls - given normal maintenance?

If used vacum for layup - would that last longer?

    

Core was Corecell. It was vacuum bagged. Every Gunboat 62 has had to address their soggy cores. Each boat takes their own path to a resolution. I didn't agree with the decision to peel the bottom off, but they've got folks smarter than me offering advice. 

 

What's shocking to me is just how loved these early Gunboats are, and how innovative and ahead of their time they were. In the subsequent 20 years since these were conceptualized by MM no one has come up with a better boat! Look at Elvis (Gunboat 6204). Full cruising comfort, 15 yrs old, and STILL smoking everything on the water.

 

If there was a replacement option for the current Gunboat owners to consider I think they'd go for it. But reinvesting in their current platform is the best path forward. A turbo'd HH is "only" 10% slower than a turbo'd 62. Dazcat? Currently they are showing a VMG average of 10 knots. Elvis is almost 15. That's night and day. 

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As for the core, any kerfed core/wet layup boat will (eventually) get a wet core. From where? Everywhere/anywhere. Sail drives, thruhulls, leaking integral tanks, deck fittings, screw holes in the bilge that allow water bilge water out, rudder bearings. You do your best to make everything waterproof, but there are lots of likely culprits. 

Wonder where my 30 year old cat had  wet core? Hulls were hand layup with Kerfed Klegecell core. Many areas were unpainted and you could see the core inside. Never any evidence of wet. Bridgedeck was thermoformed corecell, vacuum bagged. If you are careful and seal all the penetrations with thickened epoxy, then you should not have a wet core.

OK I did find one screw head that lacked adequate epoxy potting but the core wasn't wet because it was on the aft main cabin bulkhead. No real way for rain water to reach it under an overhang :)

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15 minutes ago, soma said:

Core was Corecell. It was vacuum bagged. Every Gunboat 62 has had to address their soggy cores. Each boat takes their own path to a resolution. I didn't agree with the decision to peel the bottom off, but they've got folks smarter than me offering advice. 

 

What's shocking to me is just how loved these early Gunboats are, and how innovative and ahead of their time they were. In the subsequent 20 years since these were conceptualized by MM no one has come up with a better boat! Look at Elvis (Gunboat 6204). Full cruising comfort, 15 yrs old, and STILL smoking everything on the water.

 

If there was a replacement option for the current Gunboat owners to consider I think they'd go for it. But reinvesting in their current platform is the best path forward. A turbo'd HH is "only" 10% slower than a turbo'd 62. Dazcat? Currently they are showing a VMG average of 10 knots. Elvis is almost 15. That's night and day. 

Sorry - but having to recore/skin a 15 year old (supposedly high end and definitely expensive) boat is beyond pathetic.  That they all has/had this defect is not a good excuse - it actually points to reprehensibly shoddy workmanship in the original build.  Even most carrol marine boats made it longer than 15 years...................

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It totally agree about the early Gunboats - they look much better than anything other similar  on the market - even now. And also about the performance.

 

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58 minutes ago, Christian said:

Sorry - but having to recore/skin a 15 year old (supposedly high end and definitely expensive) boat is beyond pathetic.  That they all has/had this defect is not a good excuse - it actually points to reprehensibly shoddy workmanship in the original build.  Even most carrol marine boats made it longer than 15 years...................

In the last few weeks I have been in touch with 7 owners of Kelsall foam sandwich boats which are 40+.   Trifle is the oldest at 51.   All are sound, with no structural repair ever needed on the foam sandwich.   The spec - PVC foam (70-80 kg. density),  unidirectional E glass and polyester resin - with a good 2 pot paint system.  All would be considered as light weight by today's standards.  Something is very wrong if core needs replacing after 15 years, which cannot be an easy job.  Happy boating,   Derek Kelsall.

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4 hours ago, soma said:

 

As for the core, any kerfed core/wet layup boat will (eventually) get a wet core. From where? Everywhere/anywhere. Sail drives, thruhulls, leaking integral tanks, deck fittings, screw holes in the bilge that allow water bilge water out, rudder bearings. You do your best to make everything waterproof, but there are lots of likely culprits. 

 

 

 

No offence intended here Soma, but that is just a load of Horse Shit,

That is nothing more , nothing less than, an example of extremely poor boat building. 

If you don't want to take the time and the effort and employ the skilled staff, to bed the core properly ,thats what you get.

No need to devalue  other properly built, kerfed core boats in an effort to try and gloss over Gubboats historical poor build quality issues.

(and I'm not referring to the interiors , which are lovely.)

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1 minute ago, overlay said:

No offence intended here Soma, but that is just a load of Horse Shit,

That is nothing more , nothing less than, an example of extremely poor boat building. 

If you don't want to take the time and the effort and employ the skilled staff, to bed the core properly ,thats what you get.

No need to devalue everyone other properly built, kerfed core boat in an effort to try and gloss over Gubboats historical poor build issues.

Alright. Let me rephrase myself. Every kerfed boat I've been on, from a half dozen different builders (including non-Gunboats) has had water migration issues. My formula 40 had a hole in the inner skin that constantly weaped water. It took me 8 years of looking to find where the water was getting in! It turned out it was the daggerboard trunk  

 

Honest question...what do the kerfs get filled with? Not resin, surely? Are you arguing that every skin penetration is done perfectly? Ideally, sure, you go skin-to-skin everywhere. But there are +/-1000 penetration in a Gunboat. I think it's naive to think that there is a zero chance of water intrusion...

 

I'm not in any position to defend what GB did 18 years ago. Zen was built by a 3rd party and I had nothing to do with it.  It doesn't affect the 

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Also, if I had to choose between empty kerfs that are full of water from the waterline down vs kerfs full of resin from top to bottom, I'd take salty kerfs. 

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17 minutes ago, soma said:

Also, if I had to choose between empty kerfs that are full of water from the waterline down vs kerfs full of resin from top to bottom, I'd take salty kerfs. 

Is this because of the extra weight of the resin?

If kerfed boats have this fundamental wet nature, will the 62s have to go through another round of drying the core / refiting in 10 - 15 years?

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14 minutes ago, soma said:

Also, if I had to choose between empty kerfs that are full of water from the waterline down vs kerfs full of resin from top to bottom, I'd take salty kerfs. 

First - what do we have with kerfs in PVC foam?   I assume it is water in the kerfs and not rotten core as it would be if using balsa.   My argument is that a sandwich structure is designed using the properties of the core.   Fill the kerfs with resin (which is rigid but brittle by comparison) and we have a very different situation.  If stressed the resin will break first and probably have a knotch effect on the foam core.    Some power boats suffered this failure a few decades ago, where the kerfs were half filled with resin.  Having used foam core since 1965, I never specify anything which can rot (balsa is a no no), for resin infusion small perforations are fine but avoid kerfs if you can and there is no need for the much more toxic epoxy.   Full of water might be the better structure, but disconserting then drilling the inner skin and water comes out.     Most of my boats are custom, one off and I can guarantee if the builder stayed with my spec. the structure will be good for many decades.  Derek.

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36 minutes ago, soma said:

Also, if I had to choose between empty kerfs that are full of water from the waterline down vs kerfs full of resin from top to bottom, I'd take salty kerfs. 

Thats just ignorant.

If there full of resin, thats just poor building practice. Most cruisers are so overbuilt that a few hard-spots are neither here nor there. Unsupported skin can be just as big a problem depending on design tolerances.

Good luck if hauled in a cold climate with a few  freeze thaw cycles with the kerfs full of water. 

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To clarify, there was no REAL reason to replace the core. The core WAS wet in several spots, but it wasn't rotten or delaminated. The yard and supporting designer convinced the owner it was prudent to preemptively solve the problem. I didn't agree, but it wasn't my problem to solve. Other Gunboats with similar issues didn't take that same path, either. It was a solution without a problem. 

 

Overlay, I'm comparing wet-layup vs infusion. An infused hull presumably fills the kerfs with resin from top to bottom. A wet layup presumably leaves the kerfs empty.

 

What am I getting wrong?

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As you said - the Gunboats was vacum-bagged - wouldnt that fill the voids in the sandwich - I never see that type but Divinycell as core material - routed at curvy places  - and they get filled as far as I have seen. And up here - wet sandwich will not do well during the winter....

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20 minutes ago, Derekkelsall said:

First - what do we have with kerfs in PVC foam?   I assume it is water in the kerfs and not rotten core as it would be if using balsa.   My argument is that a sandwich structure is designed using the properties of the core.   Fill the kerfs with resin (which is rigid but brittle by comparison) and we have a very different situation.  If stressed the resin will break first and probably have a knotch effect on the foam core.    Some power boats suffered this failure a few decades ago, where the kerfs were half filled with resin.  Having used foam core since 1965, I never specify anything which can rot (balsa is a no no), for resin infusion small perforations are fine but avoid kerfs if you can and there is no need for the much more toxic epoxy.   Full of water might be the better structure, but disconserting then drilling the inner skin and water comes out.     Most of my boats are custom, one off and I can guarantee if the builder stayed with my spec. the structure will be good for many decades.  Derek.

Derek,

  How is resin infused epoxy more toxic than infused vinylester or polyester? How is wet layup epoxy more harmful than the latter? I just don't buy that and yes I have looked at the MSDS for both; one of the resin systems I use nearly weakly has hardener that when in contact with aquatic life makes Chernobyl look pleasant.

Soma, I believe you are correct that an Infused hull fills the kerfs with resin. Is that better than water? Maybe, maybe not, Derek has some points concerning slamming that I won't refute. I'm curious what the other Gunboats elected to do repair wise?

-Sam

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1 minute ago, SeaGul said:

As you said - the Gunboats was vacum-bagged - wouldnt that fill the voids in the sandwich - I never see that type but Divinycell as core material - routed at curvy places  - and they get filled as far as I have seen. And up here - wet sandwich will not do well during the winter....

If enough resin is used then maybe. Vacuum bagging removes air from the system. It won't force resin to flow per se. I would argue that one of the causes for wet core can be a dry layup, but I wasn't there when this boat was built and I won't speak ill of the original builders as everyone makes mistakes.

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3 hours ago, soma said:

To clarify, there was no REAL reason to replace the core. The core WAS wet in several spots, but it wasn't rotten or delaminated. The yard and supporting designer convinced the owner it was prudent to preemptively solve the problem. I didn't agree, but it wasn't my problem to solve. Other Gunboats with similar issues didn't take that same path, either. It was a solution without a problem. 

 

Overlay, I'm comparing wet-layup vs infusion. An infused hull presumably fills the kerfs with resin from top to bottom. A wet layup presumably leaves the kerfs empty.

 

What am I getting wrong?

what you are getting wrong is the thought that this is normal after 15 years.... across the entire build set.

mate, if it is a wet lay boat, in female tooling, the kerfs will fill with the light weight bonding putty, if they were built with corecell, its prolly 'core bond' from atc. pretty light, pretty normal to fill, same kind of density as 'a550'.

 

and full of water? you are just pumping that around and through the laminate as the boat slams.

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9 hours ago, samc99us said:

If enough resin is used then maybe. Vacuum bagging removes air from the system. It won't force resin to flow per se. I would argue that one of the causes for wet core can be a dry layup, but I wasn't there when this boat was built and I won't speak ill of the original builders as everyone makes mistakes.

If you not filling the voids but use vacum - and there stills some voids under vacum in the sandwich - that will such in water/air later as soon as you make a hole for montage. The point with sandwich must be to have as much  cell-materias as possible between the skins - no voids and nob gaps filled with massiv epoxy - if its not honeycomb. So the cell material must be adapted to the shape to get this result..... isnt that so? 

 

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I'll second that on a kerfed boat, it is nearly impossible to fill the kerfs. On a Corecell boat, it is impossible, because Corecell is knife cut so the kerfs are nearly tight. You are not going to squeege or suck putty into there. But water will eventually migrate if it gets in. And it takes extreme discipline on the part of the builder (and any subsequent worker) to prevent ANY penetration of inside or outside skins. Even on many infused boats there are voids. 

Cut one of these boats apart and you'll see. 

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Hi guys,  I thought I would shed some light on this in an effort to be technically more accurate: 

  • Double cut (kerfed) core that is cut 60% deep will cause the cuts to cross and therefore all the cuts are connected. This is often used in infusion because the core can be bent to some shape and the cuts allow resin to flow through and assists also with sideways flow. Because of the ability to BEND the core without having to thermoform the core, this core is and has often  been used on a wet layup (or wet-preg) laminate.  "Core bond" is screeded on the core, core is placed down and then vacuum bag applied. Zenyatta was done like this and at the time many boats were built like this - still are! The key point is that all the cuts do not fill with resin. I think if you prefill the cuts you can probably get them full, but I am talking about a typical light-screed raceboat style corebond. So great care needs to be taken to not penetrate the skins, and to join your skins together when making penetrations. I think the mistake made was that during build or after build small holes were made in the inside skin to attach cable mounts etc. Over time these all accept bilge water. Possibly seacocks let water into the edge of the laminate, of course I cannot be sure. 
  • Double cut core, with a good infusion, will fill all the cuts with resin. Heavier, but 'safer' over the long run. Note that it is also heavier because solid resin is denser than 'core bond' which can be a resin thickened with a filler or one of the many products designed for this job. 
  • Best thing to do is use PERFORATED core, it is lightest and the holes are not connected to one another, so when water gets in it can't go anywhere. Corecell/PVC is closed-cell foam, water cannot propagate through it. Problem with curved areas like hull bottoms is that perforated core needs to be thermoformed.  Once thermoformed, this core can be 'core bonded' or infused. 
  • The Gunboat 60 and 55 were infused double cut while the new Gunboat 68 is thermoformed, perforated and infused. It should be noted that not all the South African built Gunboats (62,48,66) were built using the same methods and not at the same builder. Look at every example separately and bear in mind the incredible track record of those models in general. 

Hope the refit goes well on Zenyatta, still a great boat after many years!       

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Good information here - the builders of TRT1200 told me they used single skin in the bottom - and other round here do the same - to avoid problems with water in core and freezing, and also -if you hit something - it usually is a rock - and its rather common to do that.... and sometime you need to beak the ice...

 

Anyone... whats the cheapest a used Gunboats has been sold for? 

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Depends on if it was bought in bankruptcy or complete/bare hulls etc. The G55 that ended up in Bermuda went for pennies on the dollar.

Thanks Greenflash, all that makes total sense and gybes with my thoughts on core. Thermoforming is the correct solution, but more time consuming and expensive. The trouble with what I do is we only really know the right way to do things, i.e thermoformed cores with a minimum of relief cuts, or perforated core in certain less weight demanding applications (rare).

 

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2 hours ago, Greenflash said:

Hi guys,  I thought I would shed some light on this in an effort to be technically more accurate: 

  • Double cut (kerfed) core that is cut 60% deep will cause the cuts to cross and therefore all the cuts are connected. This is often used in infusion because the core can be bent to some shape and the cuts allow resin to flow through and assists also with sideways flow. Because of the ability to BEND the core without having to thermoform the core, this core is and has often  been used on a wet layup (or wet-preg) laminate.  "Core bond" is screeded on the core, core is placed down and then vacuum bag applied. Zenyatta was done like this and at the time many boats were built like this - still are! The key point is that all the cuts do not fill with resin. I think if you prefill the cuts you can probably get them full, but I am talking about a typical light-screed raceboat style corebond. So great care needs to be taken to not penetrate the skins, and to join your skins together when making penetrations. I think the mistake made was that during build or after build small holes were made in the inside skin to attach cable mounts etc. Over time these all accept bilge water. Possibly seacocks let water into the edge of the laminate, of course I cannot be sure. 
  • Double cut core, with a good infusion, will fill all the cuts with resin. Heavier, but 'safer' over the long run. Note that it is also heavier because solid resin is denser than 'core bond' which can be a resin thickened with a filler or one of the many products designed for this job. 
  • Best thing to do is use PERFORATED core, it is lightest and the holes are not connected to one another, so when water gets in it can't go anywhere. Corecell/PVC is closed-cell foam, water cannot propagate through it. Problem with curved areas like hull bottoms is that perforated core needs to be thermoformed.  Once thermoformed, this core can be 'core bonded' or infused. 
  • The Gunboat 60 and 55 were infused double cut while the new Gunboat 68 is thermoformed, perforated and infused. It should be noted that not all the South African built Gunboats (62,48,66) were built using the same methods and not at the same builder. Look at every example separately and bear in mind the incredible track record of those models in general. 

Hope the refit goes well on Zenyatta, still a great boat after many years!       

Droppin' science like Galileo dropped the orange!

 

What he said. ^

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5 hours ago, Greenflash said:

 Corecell/PVC is closed-cell foam, water cannot propagate through it.

While it is closed-cell foam, water can propagate through it. The cells are closed, but the matrix of cells is not 100% dense. The amount of water absorbed is low in terms of volume or weight, but it does allow some migration over time. Wide saw cut kerfs, if completely filled with resin, actually prevent migration better.

The penetration of skins at a good builder is usually well controlled below the waterline on the outside skin. On the inside skin, or above the waterline on the outside, almost no builder in the world follows the strict rule "do not penetrate without closing off". I tried to enforce this on my own boat and was only moderately successful. Trim, wiring, dodger canvas, line organizers, drink holders, furniture, picture frames, electronics - all these are hundreds of temptations to drill a hole and drive in a screw. 

There is also migration of water along the fibers of solid glass through "end grain" such as you get at properly closed off thru hull penetrations. A small amount of water is even absorbed directly by the laminate. 

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Every single cored boat whether it’s made from foam, balsa, cedar, ply or tampons MUST have EVERY single penetration cored out or routed out and  back filled. Any fucker who doesn’t do that is just a prick who doesn’t care about longevity. Sika will not do. I’m begging you. Go the extra mile. 

Water can’t travel in foam?  Bullshit. Water cant travel in crosscut balsa, bullshit? Water cant travel in cedar. Rubbish. Ply? Of course it does. 

If I had a boat with soggy wet areas I’d be devo. 

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We pulled literally 1000 self-tappers out of the inner skin on Chim Chim (6202). I'd like find whoever thought that was a good idea and kick him in the shins. 

On Chim, we removed all thru-hulls, deck penetrations, screw holes, etc. Then, we set up a vacuum bag in local areas, starting at the ends, and dried everything. We'd leave it under a relatively low vacuum for a week, trusting whatever wasn't pulled out as a liquid would evaporate. We then repaired the laminate, closed out the holes, made the skin-to-skin bond, used Weld Mount studs or Plexus (in lieu of self-tappers or through bolting), then epoxy barrier coated inside and out. It took a long time on the calendar but not much time in actual labor hours. We'd basically start the week by emptying a cabin of all hardware, and by the end of the day the bag would be on, pump running. We'd check our "sump" each day, and at the end of the week we'd take the bag off. Then we'd make the repairs and move on to the next cabin. 

 

All it itakes is one bad thruhull or whatever and the whole boat gets wet. On Zen, the integral water tank was leaking into the core. If you left the watermaker running too long water would seap out of the bulkhead around head height! My fix was to not run the watermaker too long. On this refit, they went in through the bottom of the hull (while they had the core off) and repaired the tank from the inside. The alternative was to demo the amidship head and tech space, to chop out the floor, to chop out the tank top. It was a clever solution, going in through the bottom.

 

Obviously, the hope is everything is done right and there are zero fuck ups. In reality...of course water will get in. 

 

 

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6 hours ago, SeaGul said:

Good information here - the builders of TRT1200 told me they used single skin in the bottom - and other round here do the same - to avoid problems with water in core and freezing, and also -if you hit something - it usually is a rock - and its rather common to do that.... and sometime you need to beak the ice...

 

Anyone... whats the cheapest a used Gunboats has been sold for? 

A number of surveyors promote the idea that core should not be used below the WL.  I do not subscribe to this idea.  Experience of 5 decades tells me differently.    Solid adds huge amounts of extra glass and resin.   Insulation and some impact resistance is lost.   The thin skins of decks with hot sun followed by rain are under much more pressure to suck water in.   Of course, with the right foam and the right technique, the water has no where to go.   This is why I would never use balsa.

Heat forming was mentioned.   so much depends on the amount of bend and compound curves, the thickness of foam etc.  On my first build, I used a simple oven to heat the foam before applying to the timber frame.   the problem was that the edges cooled first and tended to curl causing more problems.  In female mold with infusion vacuum pressure, should be good - heat, over-bend and then put in place.  On some projects, like wing masts, we overbend, leave for a day or more and it will retain some of its shape.

Happy boating,

 

Derek.

 

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7 hours ago, SeaGul said:

 

 

Anyone... whats the cheapest a used Gunboats has been sold for? 

I think that Rainmaker might hold that position

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I agree with Soma that some dry heat and a long period of vacuum bag should remove all water (water boils at vacuum pressure). I'd then try to suck resin through the same core laminate, if you can suffer the weight. 

I could see how water could SLOWLY propagate through core cell cells, I'll go check that one out actually. And agree double cut infused core filled with resin would stop that better to within one cell. 

Ticking all the boxes as well as not penetrating skins into core below waterline (and yes, of course this is very doable) should give you a good decades-lasting result. 

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2 hours ago, Greenflash said:

I could see how water could SLOWLY propagate through core cell cells, I'll go check that one out actually. 

 

I've already proven it for myself. 

Vacuum and heat *might* eventually dry a boat. Dry air circulation is *much* faster and can be done without much damage to the boat. 

The problem with many of the methods is that the water has to be vaporized, AND that vapor has to be removed from between the skins. You can vaporize it with microwaves, heat, vacuum, etc  - but transporting it outside the boat is a problem. If you don't it just re-condenses inside the skin somewhere else. 

It takes a very high vacuum to lower the boiling point of water much - better than 29" to get to room temp. Way more than you are likely to be able to pull on a boat hull (which also speaks to how well they are actually sealed). Raising the vapor pressure of water takes significant heat: 160 or 170 F starts to get you there, but you are cooking your boat by then. But with a few small holes (I'm talking 1/4" here) you can suck (or blow) dry air through the core with surprising efficiency. The dry air saturates on its way through and carries away the moisture. It is a slow process, but does not structurally or cosmetically compromise the hull, doesn't require exotic equipment. I've done this successfully. It is slow but not at all labor intensive. 

Another culprit in skin penetrations is plugging, poorly done. I've seen many builders drill a pilot hole, or maybe a slightly oversized one and goop it up with thickened epoxy and call it good. That isn't good enough. You need to get under the skins and bond to that, not the edge of the skin and core, and not to cling-ons of core on the skins. If you are looking at doing that for the hundreds of holes necessary to build an interior, a bonded on fastener (rather than screwed through) starts looking really labor saving. We used hundreds of threaded G10 pads in lieu of holes. Also, when back filling a core hole, the thickened epoxy really should be de-gassed, as too many times it has entrained bubbles as part of the mix, and these can create a porous backfill. 

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7 hours ago, DDW said:

We used hundreds of threaded G10 pads in lieu of holes.

Yep, you can hang pretty much anything off of G10 (Within the limits of ripping the bulkead/hull skins off!) and for the overall weight addition to the build it is a drop in the puddle and well worth the effort - I agree methods like this actually save you time in the long run, especially if you have boxes of pre-drilled and tapped G10 disks that the guys can just grab. 

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