Surprise!

Capt. Lou

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40 H&H "Julia G"
I was changing out my transducer today and to my surprise I realized my hull is cored! Foam cored I believe. I always believed it was solid glass. Last year I drilled a hole for a vent for my head and above the water line in the bow it was 1" solid glass.

image.jpg
 

Capt. Lou

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I was cleaning out the old 4200 and at first I was like "oh shit" because I was scraping some of the core out along with the 4200. I'm cool with it. Boat has been awesome. Granted this is my first downeast.
 

hntrss

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You should scrape out another 1/4 inch and backfill it with epoxy or resin/cabosil. Better safe than sorry!
 

pugsley

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What do you figure the weight savings is in this boat vs solid glass?
Plus the hull must be quieter too?

Any BIG BIG downside to a cored hull ??

my cored bruno weighs 10,800 according to the travel lift, i don't know what a solid glass one weighs, there is a solid glass one down the creek from me, and i swear my boat sits about 3" higher. when you are in crappy weather i think some weight would help, sometimes it feels like a cork.
 

pugsley

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my hull is 1 1/4 inch thick, i'm going to assume the core is 1". so that would be 1/4" of glass between the inside and outside, travis how thick are your hulls? i would think solid glass hulls are thicker than that.

it's 35 years old, and gets worked pretty hard so i guess it's strong enough
 

F/V First Team

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Like 1/2" - 3/4" depending on the area that you're taking a sample of. Up at the turn of the bilge, the seam on the two halves, way up next to the sheer flange, all of these areas can have slightly different thicknesses most generally due to the type of material used as well as the number of layers of those materials.

Every builder is different, I know of boats out there with two layers of mat, some foam core and two more layers of mat and that's it!

I would be quite surprised if you had 1" core in your boat, usually 3/4" is the standard or 1/2" if they want to build you a "light" one - again the difference in weight is only in the core material used and we're talking pounds, not any real big difference in these size vessels.
 

F/V First Team

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So the primary advantages of coring is strength/stiffness and sound attenuation?

More money to the builder...

But seriously, a stiffer product for the same amount of glass used. If the total thickness of a cored laminate was created entirely of solid fiberglass then it would probably be stiffer than its cored counterpart, but weigh more - this is where the argument of a lighter hull comes from. Sure if you are going by cross sectional thickness comparison then you would have a "lighter" hull. But if you make two hulls side by side and they use the exact same amount of fiberglass and resin in the hulls and then you add core material to one of them then that one, by default, is the heavier of the two simply because there is more material used and in that hull. Is it stiffer? Possibly depending on the shape of the hull - but keep in mind every bulkhead and deck flange that you install stiffens the hull up. Think of it like an airplane, they have very thin skins and many different bulkheads that give it the strength and rigidity to battle gravity on a daily basis.

Something to consider: a hypothetical 30' hull. It is going to take 4 barrels of resin (at 500 lbs each), 2,000 lbs of fiberglass, 2 buckets of gelcoat (@ 50/lb each) should come out weighing 4,050 lbs in a perfect world (we're going to say that there was no wasted material in the project)

Now to core this particular vessel we will need four boxes of imagina-core which weigh 120 lbs/box and two buckets of bonding material (@50 lbs/ea) So this adds on 580 lbs, not including the resin needed to wet out the core material so that if/when water is exposed to it there will be no absorbing going on. So now we weigh 4,630 lbs and we still are going to be putting in floor flanges, bulkheads and other goodies that will beef up our hull. We need to put rails on and cut some thru-hulls in, so we need to cut a hole, decore that area, fiberglass it solid, drill a pilot hole and then start mounting our piece - many additional steps and the weight of the products used to take up the space in the absence of the core material can out-weigh it by volume anywhere from 2 to 10 times. Sure if you have one single hole that's not a big deal - but if you have HUNDREDS of these holes, your weight keeps creeping up there. Higher and higher and higher. But hey, I have a "light" boat; it's cored.

Someone has to keep the oil companies in business.
 

Blitzen

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This is like the "French Model" TV commercial, "everything on the internet must be true, because it is on the internet.":D
 

Frank Grimes

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My bet is that this boat was cored (looks like with foam) to dampen sound and vibration, since it's primary function was harpooning. The first decade or so of her life I don't think the tower and stand were ever removed though I could very well be wrong about that.

I think she was built in the late 80's too, I'm surprised that the Young Brothers were coring with foam at that time. I though foam came along later.
 

pugsley

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core is stronger, as long as your core is dry, i don't believe anything in the world is stronger than a surfboard for what they weigh, and they take a lot of abuse for what they are, and only one layer of 4oz cloth.
 

Capt. Lou

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Martha's Vineyard
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40 H&H "Julia G"
My bet is that this boat was cored (looks like with foam) to dampen sound and vibration, since it's primary function was harpooning. The first decade or so of her life I don't think the tower and stand were ever removed though I could very well be wrong about that.

I think she was built in the late 80's too, I'm surprised that the Young Brothers were coring with foam at that time. I though foam came along later.

My thoughts exactly!! hull built 1989. pretty sure boat launched 1990. engine and hull are 1989.
 

Capt. Lou

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40 H&H "Julia G"
does she still have that big Lugger for power? You may have posted that before and I missed it. Any interior pics of the boat you'd like to share?

Yup still has the Lugger! Seems to be fine. Hours unknown. Was told over 10,000 how much over I don't know.

image.jpg
 

Capt. Lou

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Interior is nice and simple!
I bought these two seats to mount on port side of pilot house. I need to finish glass work next week. They should work slick. There was just a shelf and everyone tried to sit on that.

image.jpg
 
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