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Old 07-08-2009, 07:03   #31
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OG, I have enjoyed reading about your parents adventures on Tigger, what a great time they had. I don't know them but please tell thanks from me for posting their story for all to read.

Shawn

Perhaps Tom is right in saying that your Dad had it specially built with the solid hull, I too am not going to doubt a 30 year owner.
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Old 07-08-2009, 07:19   #32
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I remember reading a while back that an owner had drilled in a new seacock, and found solid glass on a T37C. He posted a pic of the plug. However, I wouldn't dispute Tom, and guess that either a few T37's out there were built custom, or that the owner whose tech article I read had drilled out one of the reinforced areas.

The Blackwatch 37 is a beaut. Similar in style to the B40, but pretty rare. Also similar, if you like the look but not the H-pricetag premium, are the Block Island 40, and the Bristol 40.
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Old 07-08-2009, 07:41   #33
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Quote: I remember reading a while back that an owner had drilled in a new seacock, and found solid glass on a T37C. He posted a pic of the plug. However, I wouldn't dispute Tom, and guess that either a few T37's out there were built custom, or that the owner whose tech article I read had drilled out one of the reinforced areas.

Yes, the owner went through a solid layup area. My hull is cored but where the seacocks pentrate the hull it is the unidirectional roving solid layup. I had the same experience as he did with a new through-hull. These areas and all high stress points are solid - the rest is cored. If a 37 owner wants to verify this, he or she can look in the storage area beneath the V-berth or in the starboard lazarette area. The sandwich construction in the underbody is quite clear in both locations.

As a piece of side info, while the deck is also cored, the high stress deck sections are solid as well. When I installed a new windlass and a deck washdown fitting, the cores I removed from the foredeck section were solid. When I rebuilt a low-stress deck area near the starboard chainplates, it was cored.

Tom
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Old 07-08-2009, 08:06   #34
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Quote:
Originally Posted by tartan37224 View Post
Quote: As a piece of side info, while the deck is also cored, the high stress deck sections are solid as well. When I installed a new windlass and a deck washdown fitting, the cores I removed from the foredeck section were solid. When I rebuilt a low-stress deck area near the starboard chainplates, it was cored.

Tom
Tom, I think that is true only on models after 1984? I will try to locate the link.
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Old 07-08-2009, 08:14   #35
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Quote: Tom, I think that is true only on models after 1984? I will try to locate the link.

My boat is a 1979 model. It has solid layup on the foredeck, under winch locations, etc. I'm the second owner. The original owner did not indicate that he had special ordered anything.

Tom
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Old 07-08-2009, 08:41   #36
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Tom,

Um, I couldn't find the article/review, go figure.

I'm certainly not implying that what your saying is not fact...however I do know this for fact, when I removed my traveler this spring and replaced it with a new one, the area where the bolts went through the deck was not solid FG, but cored, and I would consider that a "high stress" area. I now have re-bedded with an epoxy lined holes for the new traveler and bedded with butyl tape

Most importantly, the core was not wet there, I glad to see that, but that's not the case in a few other areas of the deck.

For the OP, I would add that to the best of my knowledge there are no indications of any T37 having a wet core in the hull!!! And considering the build of the hull, I don't see that ever being an issue as long as the owner maintains their boat with a barrier coat and there is no puncture of the hull.
Also I can confirm the hull is solid where the transducers are located as I just replaced the OEM units with new Airmar transducers...solid and thick, about 2"
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Old 07-08-2009, 09:07   #37
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Mine is also NOT cored at the traveler area. Go figure! I installed some fairly heavy stainless steel backing plates there when I had the headliner removed.

Your thoughts on the hull are spot-on. Because of my involvement with the web site and the book, I've had contact with a great number of T37 owners over the years, and the hull has not been a problem.

Deck repairs are sometimes needed, generally because fittings were mounted without regard for proper hole sealing. Unfortunately, that was all too common in older cored-deck boats, including the Tartan 37. When cored decks were first built, nobody thought about the effects of water intrusion and saturation on the core. They just drilled through, installed some bedding compound, tightened the fittings and moved on. I've addressed all of those instances on my boat by grinding out the core using a bent nail in a drill chuck, vacuuming out the loose particles, filling the area with West System and re-drilling through the solid patch. I have had no deck issues since.

Tom
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Old 07-08-2009, 09:10   #38
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OOPS! On my last, I meant to say that the hull was also NOT SOLID at the traveler area! In other words, just like yours.

Tom
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Old 07-08-2009, 09:28   #39
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Great job with the book BTW, I love it, great way to preserve the history of a great boat.
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Old 07-08-2009, 12:39   #40
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This is one of many reason I love boats, I am always learning Two days ago I would of bet a million dollars that Tartans are not cored hulls - just when you think ya know someone they turn out to be cored I am sticking with the "special hull order" in Tigger case out of loyalty to me dad. They did have to dig out the aft part of the foredeck and replace the cored deck, but she was 20 (ish) and had been around the world-gal deserved a FBG botox .
I will let them know about all the good wishes. Sorry if I hijacked the thread-
Cheers,
Erika
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Old 07-08-2009, 13:19   #41
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"The outer layer of FG is more than a 1/2 inch thick before the balsa, and only 1/2 or so after. " surely this cant be right? 1/2" either side? that's really two boats, one floating in balsa!
Also, if coring is so strong, why are we calling the solid glass areas the High Stress areas? :>)
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Old 07-08-2009, 13:50   #42
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With the risk of getting beat up here, and knowing that Tartans have a reputation for being swift, well built vessels, I don't think the two are in the same leauge?
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Old 07-08-2009, 13:57   #43
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Quote:
Originally Posted by Cheechako View Post
"The outer layer of FG is more than a 1/2 inch thick before the balsa, and only 1/2 or so after. " surely this cant be right? 1/2" either side? that's really two boats, one floating in balsa!
Also, if coring is so strong, why are we calling the solid glass areas the High Stress areas? :>)
Um, I think I exagerated Here is a pic of the hull opening for the transducer where it is solid FG.
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Old 07-08-2009, 14:29   #44
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Quote:
Originally Posted by Cheechako View Post
"The outer layer of FG is more than a 1/2 inch thick before the balsa, and only 1/2 or so after. " surely this cant be right? 1/2" either side? that's really two boats, one floating in balsa!
Also, if coring is so strong, why are we calling the solid glass areas the High Stress areas? :>)
That's a good question, deserving of a slightly technical answer. Other Engineers and similar types please bear with me - I'm going to assume that some of the folks reading this have less technical backgrounds.

The solid layup is for LOCALIZED stress, such as large point loads and through hulls. This is where you are applying loads at a point, and the load is basically perpendicular to the surface. The core would not lend any strength to speak of in these areas.

The cored hull allows the constuction of a greater hull thickness for overall stiffness, without the excessive weight that would come with a very heavy solid layup. As an example, think of a steel Wide-Flange beam - laymen prefer to call them I-beams. They have a relatively thick top and bottom flange, connected only by a realtively thin vertical section, called the "web". When you try to bend the beam by placing a load on top of the upper flange, the bending is resisted when the top flange is compressed and the bottom flange is place in tension. The farther apart these two opposing resistance areas (the flanges) are, the greater the stiffness of the beam, and the more resistant it will be to bending.

Now consider the hull. If you take two 1/2" layers of fiberglass and simply put them directly together, they will resist bending but only to a degree. To stiffen the hull, you need greater thickness, or separation between the reistance to tensile and compressive forces. When you move the layers apart, you need something to fill the space and create a connection between them so they will act in concert. If you use more fiberglass as that connection, you add a lot of weight. By using the balsa core, you gain distance between the tension and compression resistance and add very little weight at all -- so you get a light but stiff hull. The balsa performs the same function as the web section did in the beam example.

Hope I didn't bore everybody, but the question was a good one.

Tom
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Old 08-08-2009, 04:20   #45
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Excellent explanation, Tom.
Ideally, both “solid” laminate skins should be the same thickness.

Jeff H gave an excellent Primer on Fiberglass Construction (see post #1), which led to an enlightening discussion
A Primer on Fiberglass Construction

Belowhttp://www.cruisersforum.com/gallery...r&imageuser=79
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