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Old 04-29-2019, 08:42 AM   #21
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Originally Posted by Simi 60 View Post
Bloody contour foam
Voids very rarely get filled during the layup.

I have done repairs before where we drilled a 2 inch hole through the skin, removed, fitted vacuum pumps and sucked out several hundred litres of water over a week.
Foam was fine and still attached
Several hundred liters from a single 2" hole? impressive..
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Old 04-29-2019, 08:44 AM   #22
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What do you think will happen when it is your turn to sell the boat?
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Old 04-29-2019, 08:47 AM   #23
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IMO the strength of a cored hull comes from the box structure created by bondind an outer and inner skin with a web created by core. Similar to an I beam. In those PIX the outer skin is loose from the core so there is not the box structure strength.
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Old 04-29-2019, 02:13 PM   #24
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That is why I preffer older boats with no core.
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Old 04-29-2019, 03:10 PM   #25
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Do you know if KK used solid glass around the thru hull fittings? I found this article very informative...
Our 42 has solid glass at the hull penetrations or at least on the five that we’ve removed (transducers and/or thru-hulls). What I don’t know is if the core was removed before or after the hulls were laid up.
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Old 04-29-2019, 07:27 PM   #26
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Ok.. Lots of great information and feedback.

Are there any trawler makers that have solid fiberglass hulls AND solid superstructure and or decks?

Thanks in advance for replies.
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Old 04-29-2019, 07:37 PM   #27
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If you link my google photo album, I would appreciate if you linked the blog as well to explain what is happening, and give them contact information to answer questions vs. everyone speculating about what they are looking at.
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Old 04-29-2019, 07:38 PM   #28
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I would talk to Tom Button at Kadey Krogen. He’s been around longer than most of the staff there. IIRC, the later models of KK42’s were solid below the water line but I don’t have information on the hull number when that changes. Tom would know.

http://www.kadeykrogen.com/our-story/staff/
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Old 04-29-2019, 10:06 PM   #29
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Originally Posted by palasz View Post
Ok.. Lots of great information and feedback.

Are there any trawler makers that have solid fiberglass hulls AND solid superstructure and or decks?

Thanks in advance for replies.
I wouldn't worry about the cored superstructure and decks. A large percentage of the members of this forum have them. 😉
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Old 04-29-2019, 11:36 PM   #30
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It`s significant imo that KK went from cored to solid below the waterline.
I explored this issue in relation to a Beneteau,all of which are balsa cored below the waterline. I decided that cored above, and cored superstructure, were fine, but cored below is a no no. At a minimum, every skin fitting comprises a risk.
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Old 04-30-2019, 06:10 AM   #31
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The KK with a bottom job because the Airex was not properly stuck to the outer hull is an old problem of then current construction technique..

Today with modern vacuum tech this problem no longer exists.

A vessel with topsides , deck and pilot house in solid GRP would be very heavy .

Solid GRP below the WL tapered where connecting to the topsides , with good foam cored deck and PH would be about as safe as can be done , even with 3rd world labor.

In a top of the line shop cored & epoxy vacuumed would be fine , but mostly for the lighter weight and perhaps slightly faster speeds on the plane .
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Old 04-30-2019, 08:23 AM   #32
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Originally Posted by palasz View Post
Ok.. Lots of great information and feedback.

Are there any trawler makers that have solid fiberglass hulls AND solid superstructure and or decks?

Thanks in advance for replies.
Palasz
As a subset to your question - during the past decade, are there any builders of "trawlers" that use core below the waterline? If yes, I'd argue they are weight saving planing hulls using the trawler moniker for marketing purposes only.

The FRP list of current cored power boats of any type between say 30 to 60 feet (below the waterline) is pretty small.
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Old 04-30-2019, 08:39 AM   #33
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Can a wet cored hull be replaced?

Quote:
Originally Posted by palasz View Post
Ok.. Lots of great information and feedback.

Are there any trawler makers that have solid fiberglass hulls AND solid superstructure and or decks?

Thanks in advance for replies.


Literally none. Solid fiberglass decks and super structures would have a dramatic adverse effect on stability due raising the CG. For the same reason most steel hulled boats have aluminum superstructures in order to keep the weight low.

Additionally, coring does add rigidity to decks.
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Old 05-06-2019, 01:00 PM   #34
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Follow up:

I contacted a few companies that repair hulls and learned A LOT from one East Coast shop. Wet, cored hulls can be repaired and the cost is 400 to 500 dollars a square foot. Once the repair is complete it is supposed to be better than before and future problems would be minimal...that was my take home message from the conversation.

So, on a 52' KK I am guesstimating 300 square feet or more of repair below the waterline... Just another big number to factor into the buying equation if a future repair is needed..
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Old 05-06-2019, 01:18 PM   #35
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KK 42 are great boats; arguably one of the best for long distance cruising. There was a KK 42 in Pensacola Naval Shipyard for almost a year drying. Had carbide blade Peel, then low humidity, sealed and heat. Next "Hot Vac"--heated pads with vacuum constantly applied. Final solution was "Hot Vac" with thousands of small holes drilled in outer laminate--and got her dry. The outer glass layers were then re-laminated with epoxy. There may be better techniques now.

We were looking at a number of laminates during delamination non destructive testing instrument development studies. Among the samples we worked with were cut outs for a KK 42 bow thruster. We eventually dried them in an oven. The amount of water appeared to be more than what would be expected on the surface. (Dry weight vs initial "wet" weight) Despite being wet, the bonds to fiberglass on both sides were excellent. That boat had spent its life in warm water. Many boat owners, especially with thick laminates, elect to just repair blistering and any delimitation as it occurs, and not do the expensive "solutions" of attempting to completely dry the core and laminate.

Keep in mind that there are a number of "Airex" foams. Some are claimed to adsorb no water, others low amounts of water--and some there is no statement. With time it is not unusual to have some breakdown of various foams. Freeze thaw cycles are one insult to foam, as is pounding or actual crush damage to a core.

My own small cruising vessel has a cored, but dry bottom. I believe you are wise looking for a dry or solid glass bottom CC 42/44.
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Old 05-06-2019, 04:20 PM   #36
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Couple years ago there was a kadey krogen manatee in marathon that was for sale for $12,000 ,,,I was going to buy it but found out that this boat hasn't been hauled out in 25 years and a yacht broker told me the straps will crush the hull when lifted so I backed off. Now i'm pissed because that boat was hauled by the new owner with no problems and sits nicely in key west today. YACHT BROKERS.
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Old 05-06-2019, 06:03 PM   #37
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you had plenty of suggestions but I will ad my .10 cents worth anyhow. Barretts Marine in Spring Lake, Michigan were I keep my boat has dried out plenty of hulls in the 8 years that I have been here. Its a lengthy process but well worth it.
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Old 05-06-2019, 06:11 PM   #38
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Quote:
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Palasz
As a subset to your question - during the past decade, are there any builders of "trawlers" that use core below the waterline? If yes, I'd argue they are weight saving planing hulls using the trawler moniker for marketing purposes only.....
Top of any list would be Beneteau which as discussed previously, I believe builds cored hulls in every boat they make.
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Old 05-07-2019, 07:06 AM   #39
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One of the YouTube channels I follow is Sail Life.

Basically a major refit of a Warrior 38.

The core of his hull was wet, he designed and built his own hot vac system to dry it. His channel is focused on the entire project, not just drying the hull, so the info is sprinkled over several videos.

He shows some of it between minutes 4:00 and 6:30 of this video.


He did his complete hull, while hauled.
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Old 05-07-2019, 11:18 AM   #40
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We looked for a used KK 42 back in the late 90's. We loved the look of the KK42, its displacement hull, large tankage and the single Lehman. Most we looked at were selling for around $200K. They all had water in the coring which caused the hull to deform between bulkheads. The cost to repair the deformed hull and remove the water at the time ranged from $65K - $85K. The repair at that time was done from the inside so tanks had to be removed.

We had Matt Harris as our surveyor.

Jim Krogen was alive then and answered the phone frequently. The Katy Krogen company was still pretty small in those days. He told me that there were periods in the 80's when his representative was not in Taiwan overseeing KK 42 construction and the yard would substitue materials without notifying KK. Jim Krogen said the yard would use non marine plywood and foam coring manufactured in Japan as substitute for the Airex and marine ply.

Jim Krogen said they started building solid bottoms around 1995 but still used foam in the sides of the hull.

Jim Krogen said he would not own a pre 1995 KK42 because of the issues with the foam. He was adamant about that but expressed regret over boats bearing his name with a latent defect.

We bought a 1976 Bluewater 39 Pilothouse Trawler, which has a solid FG hull, with a single Lehman in 2000 that we still own.

The Bluewater has issues too with a plywood cabin sides and roof rotting from water intrusion. But the top sides are easy to repair in comparison to drying and repairing a cored hull. Other than the faded gelcoat the hull has been maintenance free for 20 years
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