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  #31  
Old 10-19-2010
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If a dirty bottom slows you down what do you think it does to your boat
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  #32  
Old 10-19-2010
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Quote:
Originally Posted by tommays View Post



looks worse than it was


big area of damage at the blue paint well behind the keel

Its the LEAD keel on Zzzoom which dinged a rock at 7 knots healed at about 15 degrees

When the PO owned the boat he hired Britton Chance to do several keels a modern double spreader rig and rudder years back

The C&C 35 I has no sump or bilge to speak of for that matter

The new keel was much deeper 7' and a shorter mounting footprint so to take the load and support the mast which NO longer had the BIG original keel under it

They really beefed up the hull and it never had and issues with the smile UNTIL the rock and it had no smile after the rock

The lead did not yield at the hull at ALL

Small amount of hull damage forward and aft of the keel

Massive damage 2' behind the keel were the hull was finally weak enough to yield to the massive force involved


I have another friend with a Tartan 372 that hit a ledge in Maine and in the finest mythbusters BUSTING myths it broke all kinds of stuff on the boat like all 4 motor mounts

I assure running aground is NOTHING like hitting a unyielding rock and lead or cast iron your screwed and the boat is NOT gonna be OK
Thanks for extra pics. I'm thinking that hitting rock has got to hurt to some extent and the faster you are travelling the more it will crunch.

To me your pics appear, and I emphasise appear, to indicate that leverage had as much to do with the end result than impact as such. Deep keel, striking down low. What does she draw btw ?

Fool....your boat..what is she ? what does she draw ?
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Last edited by tdw; 10-21-2010 at 04:30 PM.
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  #33  
Old 10-20-2010
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Quote:
Originally Posted by Cruisingdad View Post
Not sure, but I think Hallberg-Rassy?? I do know they also use a grid system and think it is a hand laid solid GRP.
HR is a foam sandwich above waterline. They call it insulation, to avoid all bad publicity

Nauticat is all fiberglass, there is no sandwich anywhere, not even in a deck.

Sandwich
1. Either stronger at same weight or lighter at same strength
2. Rigid, less or no flex
3. Better insulation, both thermal and acoustic, no running water from sides, warmer boat.
4. Lesser internal structure. It is easier to customize interior since it doesn't depends on internal structure of a boat as much as true fiberglass boat's interior.

In about every aspect, sandwich is better material, as long as it stays whole.

Talking from experience here, I already recored about 1/3 of my boat
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  #34  
Old 10-21-2010
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Quote:
Originally Posted by tdw View Post
....
Fool....your boat..what is she ? what does she draw ?
C&C30 I, Beneteau First 30E, both about 5'6' CS-36T 6'3". On severe impact the CS was exposed to stringer damage although not my experience.
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Last edited by tdw; 10-21-2010 at 04:31 PM.
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  #35  
Old 10-21-2010
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C&C30 I, Beneteau First 30E, both about 5'6' CS-36T 6'3". On severe impact the CS was exposed to stringer damage although not my experience.
Thanks.
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  #36  
Old 10-21-2010
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This isn't directly relevant to your purchase, TD - but on the subject of cored hulls:

I still remember wandering around the CYC marina after we withdrew from the 1985 Sydney-Hobart race marvelling at the damage to the many other boats that withdrew. You could see which tack they'd been on at the time the front moved in, because on more than a few of them the high-side windows were smashed in and the low-side hull rippled like corrugated-iron with the rib/bulkhead positions clearly showing outside - basically the core had been crushed by the impact of the boat launching off the waves for hours on end.

OK, that's pretty extreme conditions and it shows there is a definite limit to how far a hull core can be pushed before irrepairable damage occurs - but it seems to me this limit is set by the designer/builder and is NOT going to be all that evident to the yacht's owner.

Unlike steel, wood, aluminium, or solid GRP/Kevlar/CF where thickness is roughly proportional to strength, because of it's multiple parts working together I know of no easy way to tell what an existing cored structure can stand before it fails. Just saying..
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  #37  
Old 12-27-2010
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Cored hulls sound great as far as strength and weight..I see why Farr and other racer/cruisers were built that way....but overall aren't balsa cored boats hugely susceptible to water ingress thru any fitting/bolt hole that might happen to not be seated/bedded properly..?

In any boats more than a couple years old...how would you know if it isn't riddled with soggy balsa..a few posts above Crazy Ru really seems to seal the deal for me with his comment that 1/3 of his boat has been re-cored..

Solid hulls built with good panels/stringers seems to be the way to go for those who aren't after racing-type speed necesarilly and who don't like the prospect of a re-core in the future...cored hulls have their merits for those who need the speed and can afford to have the hull or decks re-cored down the road...may not be far down the road though...who could know without core analysis with a moisture meter... or a really great surveyor?

As for me..I have enough things to fix on my old boat without the disturbing thought of doing re-core. I may eventually add horizontal stringers in select places like the chainplate area one day or re-do my bulkheads and fillet them into the hull,etc,etc, and many cored-hull boats were built with panels and grids that make them very strong..it's the balsa that is the problem...the new foam sandwich also has its share of rpoblems though from what I have heard..maybe this is being addressed though now...any thoughts from the gallery are appreciated...I thought this was a good thread that died too young...

Last edited by souljour2000; 12-27-2010 at 09:54 PM.
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  #38  
Old 12-27-2010
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A cored hull if well built has less issues than a cored deck with the dozens of fastener holes to deal with. And probably 95% of glass boats of any size have cored decks. Well built means a controlled layup, vacuum bagged ideally, and every through hull or penetration with solid glass surrounding it. Solid glass on the center line and in way if keel area. A hull built this way should not have a wet core issue. If it is damaged in any way the only way water will be absorbed is if it is not repaired promptly.
Most multihulls are cored as well as more and more monohulls. Like any advanced construction method quality is important. But if it is done well I see no reason to stay away from cores.
As far as buying an older boat that is cored, whether deck only or hull and deck, a surveyor familiar with core construction should not have a problem finding any issues. A moisture meter is a good investment for anyone interested in buying a fiberglass boat as they almost all have core somewhere. They are not hard to use and can save paying for a survey on a boat with wet/moist core. Here's a link by Maine Sail explaining how to use a meter and what it can do for you.
Understanding the Moisture Meter / Electrophysics CT-33 Photo Gallery by Compass Marine at pbase.com
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  #39  
Old 12-27-2010
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good points tiempo...I guess a cored hull is okay enough if it's sealed well and built well but cored decks scare me..The only cored area of my Seafarer 24 is the balsa -cored anchor locker lid and I already re-built that..have alot of other issues typical of old boats though...but replacing decks is not one of them thank god...

Last edited by souljour2000; 12-27-2010 at 11:59 PM.
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  #40  
Old 12-28-2010
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Don't be scared of balsa cored decks. They're everywhere and it's a good bet your next boat will have one.
Even a cored deck without solid glass around fastenings is not always a disaster. Definitely not the way to build, especially with what we now know, but as long as the hardware was bedded properly and rebedded periodically as necessary there isn't always a problem.
A new boat with solid glass around every hardware penetration through core should not have issues. A used boat from the 70's or 80's may or may not be a good purchase if the core is wet depending on extent. But if an older boat is purchased, ant wet core replaced, epoxy around all hardware fastenings and the hardware properly rebedded, which is a good idea on an older boat in any case, it should not have future issues. The problems we see on 20 year old boats now are not just the result of a core being there or bad construction practices, but also of lack of maintenance that the boat deserved.
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