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Old 22-06-2012, 05:20   #16
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Re: Glue for keel to hull attachment

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Originally Posted by AussieWayne View Post
MacG
The keels are designed as sacrificial so that they can break free if they encounter an underwater obstacle without breaching the actual hull. A good design feature I would think but not sure if that is how it actualy works in reality and don't really want to test that part at any time!
I am still waiting on a further response and advice from FP as to sikaflex and or sealing the parts before re attachment.
Wayne
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Frankly, I cannot see the overall benefit of such a construction. But again, I have no experience with big cats. Constructionwise, I would reject such a design. To me, it makes no sense.
When we were in Raiatea we learn't that this is a common occurence in the charter fleet when an "inexperienced bareboat charterer" will hit a coral bomby or.....? The keel will break out with no integral damage done to the main hull of the boat. Close inspection of the sacrificial keel will show a hole at the bottom aft corner. This is so that the keel may be retrieved and towed back to the charter base for a refit of the keel.

Shock resistant fins for sailing:
The keel to hull attachement is a key element of catamaran safety and has been patented by Fountaine Pajot. No other catamaran manufacturer can offer this protection. For safety reasons, the fins are completely separate from the hulls, a feature which preserves and protects the water tightness of the vessel in the event of a violent impact. Unlike other builders who laminate and bolt their keels – which in case of a collision could rip out the bottom of the hulls, Fountaine Pajot connects them in a watertight cavity that is integrally moulded to the hulls. In addition to this safety system, if a keel is damaged, it makes them easier to repair or replace and normally takes less than several hours.




Sikaflex, I believe, is what you need. Hope you hear from FP soon. Love to know what they recommend.

Cheers
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Old 22-06-2012, 05:49   #17
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Re: Glue for keel to hull attachment

My opinion: You add another obstacle to the Cat's hull: when you hit something it is mostly bow first and than comes the attachment of the keel to late. In other words, the attachment of the keel provokes problems rather than preventing them. The only (reduced) advantage I see is that it works as a sort of daggerboard, minimalising drift.

It is a designg feature that you might or might not appreciate. I wouldn't have it, I would look for other solutions to reinforce the keelsom.
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Old 22-06-2012, 06:54   #18
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Re: Glue for keel to hull attachment

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Originally Posted by MacG View Post
My opinion: You add another obstacle to the Cat's hull: when you hit something it is mostly bow first and than comes the attachment of the keel to late. In other words, the attachment of the keel provokes problems rather than preventing them. The only (reduced) advantage I see is that it works as a sort of daggerboard, minimalising drift.

It is a designg feature that you might or might not appreciate. I wouldn't have it, I would look for other solutions to reinforce the keelsom.
Unlike monohulls, cat's don't require weighted keels, hence you are correct in that the keel in question is simply a 'daggerboard'.

I will somewhat disagree that the majority of groundings are 'bow first'. Assuming there is a human at the helm that is watching forward, the majority won't intentionally run aground when the can see the ground. Since the ability to see underwater at a distance diminishes quickly the deeper the object, most groundings are hitting something that is 2+' deep (below hull level on a cat).

So the design question is whether to make the keel on a cat an (1) integral part of the hull or (2) not.

1 - If you breach the keel, you'll flood the hull.
2 - If you breach the keel, no water in the hull.

Since the keel on a cat isn't heavy it's not trying to constantly sink the boat, hence the attachment mechanism only needs to account for the lateral forces of the underwater wing during sailing upwind. FP has designed an attachment method that does not require breaching the hull. I see this as a positive when compared to lifting the sole in competing manufacturers boats and looking at a bilge pump in the bottom of a 3' hollow keel that is 3" wide (requiring a 3' long screw driver to remove/install). You damage this keel and must pray the bilge pump can keep up with until you get repaired.

I believe the design is proven, as any major maintenance on the FP keels is due to hard groundings, which would require keel work on any boat.

All IMO, or course!
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Old 22-06-2012, 07:16   #19
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Re: Glue for keel to hull attachment

I see your point(s) but living in Holland with it's many shoals like sandbanks, mudbanks and the shoals of the Wadden and Frisian lakes learns you to navigate with care and having owned a very deep keeler monohull (over 8') I nonetheless crossed the Wadden quite often on the edge of beaching when the tide was running slow. A sounder is a very MUST for us and my new boat has been chosen to make it easier to go into the shoals.

Now the US and Carib is different - there are corals, sometimes charted, sometimes not.
But if the bow doesn't hit first but the boxkeel does, it is still an extra p.i.t.a.
A sounder with a bit forward action would be of much more use.

Anyway, I am a monohuller and do look differently at such issues. The sole case I seriously beached was caused going solo along the Spanish coast and the eggtimer was not able to woke me up. I was overexhausted and fell asleep behind the rudder.
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Old 22-06-2012, 07:45   #20
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Re: Glue for keel to hull attachment

It sounds like a clever idea (shearing off keel fins) but then why not use a shear pin, as with outboard props, instead of a mess of glue? Or for that matter, Velcro. <WEG>
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Old 22-06-2012, 07:49   #21
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Re: Glue for keel to hull attachment

Or center boards...

cheers,
Nick.
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Old 22-06-2012, 14:18   #22
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Re: Glue for keel to hull attachment

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It sounds like a clever idea (shearing off keel fins) but then why not use a shear pin, as with outboard props, instead of a mess of glue? Or for that matter, Velcro. <WEG>
I haven't thought about it as the current system seems to work. We do pay attention to it at haul-out time, if only to verify the chalking around the seam.

I would guess anything different than glue would probably add to the cost with no return on the investment, unless/until you knock off a keel. Of course, if you are one of the 'unfortunate' who does, you'll probably just pay to get it fixed and not complain about the cost due to embarrassment.

I do like the velcro idea!


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Originally Posted by s/v Jedi View Post
Or center boards...

cheers,
Nick.
I'm sure those that possess the inclination to separate the keel from their FP hull would certainly be very likely to forget to raise the center board!
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Old 22-06-2012, 16:19   #23
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Originally Posted by DotDun
I'm sure those that possess the inclination to separate the keel from their FP hull would certainly be very likely to forget to raise the center board!
Ahhhh..... they profiled the avg buyer

cheers,
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Old 22-06-2012, 16:37   #24
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Re: Glue for keel to hull attachment

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Ahhhh..... they profiled the avg buyer

cheers,
Nick.
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Old 25-06-2012, 20:22   #25
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Re: Glue for keel to hull attachment

Thanks to everyone for all the advice. Especially KiwiKat and DotDun your explanations and advice are certainly along the line where I was thinking.
I know what choice I would make if I had to choose between a hollow keel open to the hull or a foam filled keel designed to absorb impact by breaking away if an impact occurs and leaving the integrity of the hull intact. The automobile industry has used a somewhat analogous theory for many years by building in crumple zones designed to absorb impact into the front of vehicles.

Fountaine Pajots original advice was to use urethrane (Sikaflex) around the landing seams to secure the keels.
I then emailed Fountaine Pajot the following query

Thank you very much for your earlier advice, it is much appreciated.
If water has been leaking in to the keel box between the top of the keel and the bottom of the hull for some years would Fountaine Pajot recommend the complete removal of the keels then re application of the polyurethane glue or would it be possible to achieve a satisfactory and long lasting result to just reseal along the joining seam?

During original manufacture in 2002 how were the bottoms of the hulls and the top of the keel mould protected should water ingress occur through a leak in the joining seam? ie:Are they painted with epoxy and further coated with any antifoul paint? Or is it just untreated FRP between that keel to hull section?
Or is it just the exposed foam? If so then would epoxy glue be best to use then?

Is it indeed possible to remove the keel from the hull keel box without doing damage to either part and are there any guidelines published by Fountaine Pajot on how to do this?
Can you provide any photos of the separated keel and hull keel box?

Once again thank you for your assistance on a very important problem.
Please advise
Kind regards
Wayne


I am still waiting for an answer to this query

If/when I get an answer I will post the result just for the record.
Wayne
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Old 25-06-2012, 20:55   #26
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Re: Glue for keel to hull attachment

Good luck Wayne, I'm still waiting for an answer on what to do about my hull blisters.
All they will say is "it's not covered by warranty".

Personally I would be amazed if they bothered to seal the keels before they installed them.
2002 was the start of the osmosis epidemic and sealing the tops of the keels was unlikely to be a consideration.
They are very cagey about admitting any shortfalls in their manufacturing process even on older boats so I think we both will have a long wait for a reply.
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Old 25-06-2012, 21:05   #27
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Re: Glue for keel to hull attachment

2 months ago i was sailing with a buddy boat on the south coast of Cuba where navionics are not accurate. He hit a reef at 3 am doing 8knts , full sails. The cat ramped over the reef due to the slant on the fwd section of the keel and into another reef. The cat sat on the reef for 5hrs grinding away. Eventually the keels broke away and we managed to get her off. She sailed a futher 500miles before repairs could be done. Sacrificial keels WORK. Had it been another type of Yacht , the outcome would have been very different.
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Old 25-06-2012, 21:32   #28
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Re: Glue for keel to hull attachment

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......Personally I would be amazed if they bothered to seal the keels before they installed them.
2002 was the start of the osmosis epidemic and sealing the tops of the keels was unlikely to be a consideration.
I wouldn't associate the sealing of the keels with the osmosis issues. You can track the osmosis problems to the change in the build technique, it seems the problems started as they moved from vacuum-bagged to infusion. I don't believe there was a lower quality of craftsmanship across all models during that timeframe.

Although, I have no clue if the keels are or ever have been sealed on any model.
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Old 26-06-2012, 05:27   #29
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Re: Glue for keel to hull attachment

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Originally Posted by chris smith View Post
2 months ago i was sailing with a buddy boat on the south coast of Cuba where navionics are not accurate. He hit a reef at 3 am doing 8knts , full sails. The cat ramped over the reef due to the slant on the fwd section of the keel and into another reef. The cat sat on the reef for 5hrs grinding away. Eventually the keels broke away and we managed to get her off. She sailed a futher 500miles before repairs could be done. Sacrificial keels WORK. Had it been another type of Yacht , the outcome would have been very different.
Chris that is a great testament to the validity of these sacrificial keels.
It certainly endorses some of the comments made here earlier so thanks for that.
Sure glad that it turned out a lot better for your buddy than it otherwise could have been. Hopefully they have had their repairs done and are back out there cruising.
It would be great if they could tell us of their experience of the incident, what it was like to sail 500 miles without the keels and just how they were repaired or manufactured and refitted. Could be quite eductaional for all of the FP sailors. By the way do you recall what FP your buddy boat is?
Kind regards
Wayne
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Old 26-06-2012, 05:34   #30
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Re: Glue for keel to hull attachment

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I wouldn't associate the sealing of the keels with the osmosis issues. You can track the osmosis problems to the change in the build technique, it seems the problems started as they moved from vacuum-bagged to infusion. I don't believe there was a lower quality of craftsmanship across all models during that timeframe.

Although, I have no clue if the keels are or ever have been sealed on any model.
DotDun do you know the timeline and the models involved for this change from vacuum bagged to infusion? Do you have any further info on this or possibly a link to further info.
If FP ever answer maybe we will have the answer to whether the keels and keel boxes were ever sealed in manufacture.
Thank you
Kind regards
Wayne
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