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Old 21-06-2013, 22:19   #16
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Re: Initial Interest in Prefabricated Composite Panels

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Originally Posted by beiland View Post
Let me go back a year or so and reference a forum discussion I entered when I became real interested in this 'prefabricate composite panel' subject.
Are Cats Made from Duflex Panel Kits Strong ?

I had known for a number of years about these various kit-boat designers/builder in Australia, and NZ. I had just never really studied about the 'composite panels' they were using. And I was confused about the various 'brand names' being applied to these panels. That's how I came to following this subject thread.
Are Cats from Duflex Panel Kits - Strong?

Then I began to look more throughly at the Propropylene honeycombs rather than the balsa and foam cored products,....ie, NidaCore, Plascore, Polycore. I knew of these as well, but had always rejected them



Then I discovered this kit-boat, The Solitary Island 12M Cat
http://www.multihull.com.au/site/www...fic_40_kit.pdf

Regrettable they had to stop their project due to economic times of the past few years, and a number of the web pages relating to building these kits were taken down. Here are a copule of more sites I find now.
DIY Yachts • View topic - Solitary Island 12
http://polycorecomposites.com/News--and--Events.php

After quite a bit of reading about PP honeycombs, I'm convinced they made VERY good core material for sandwich construction. And in the 'prefabricated sheet form' they are superior to foam panels, or balsa panels, or plywood, etc.

Compatibilty with steel?
Realize that one of the enduring properties of steel is its 'ductility', ...it is forgiving under an impact load. PP honeycomb also is ductile, in fact so much so that it outperforms the plywoods, and the foam cored panels and the balsa cored panels. You can find some proven test about this. This stuff will make GREAT decks.

Now all we need to do is properly bond these sandwich panel decks to the steel hulls. (And I think this is going to be much easier than bonding plywood or aluminium to the steel). Have you looked at the GREAT advances we have in bonding adhesives these days?
Plexus for one.. http://www.itwplexus.com/UserFiles/F...ectorGuide.pdf
They have been bonding deck-to-hull production boats for a number of years now, and often without any other fasteners, etc

3M 5200 could likely do the job.

With a little research I'm sure we can come up with the best bonding agent for this application. And with proper care the correct 'landing' can be built into the steel hull to accept this composite deck.
Yes 3M are the go, the Adams designs used Sika and SS bolts incorporating a toe rail on the joint but mainly just drilled and tapped into the 100x6 SS margin plate, and no the SS didn't disappear in a bubble of rust in leiu of Titanium...
Frank
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Old 21-06-2013, 22:22   #17
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Re: STEEL HULLS with Composite Superstructure / Topsides

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Composite construction used to be fairly popular in the '50s and '60s. A number of steel hulled boats built mostly with wooden decks and maybe some with Aluminum, the SS United States for one. SS United States - Wikipedia, the free encyclopedia I've looked at a couple of wooden decked steel boats and the problems with the wood steel interface and the deck itself were just insurmountable for me. If you could get a reliable long term seal of the deck material to the steel hull it might be a practical means of construction. Just doubt that a permanent seal and prevention of corrosion at the joint is possible and would be the achilles heel of any composite construction technique.

Steel is a wonderful material for a virtually indestructible, by exterior caused damage, material for a boat but the maintenance is a major headache. There are ways to keep the rustermite at bay but none are permanent. Constant diligence is the lot of the steel boat owner. Have had two steel cruising boats here this year. Both were fine examples of steel construction but both spent most of their several months stay in the harbor dealing with corrosion issues. It's not only the deck and topsides that are the problem though apparently the bulk of the issues. Any small nick or scrape below the water line requires a haulout, grinding to bright metal, sealing with epoxy, and repainting. Not an overwhelming task but just something that can't be ignored or put off for long without dire consequences. Remember talking with Bernard Moitessier and him complaining that he'd had the deck of Joshua rust through in a few places cause he hadn't been diligent enough with maintenance.

Yes, there may be a market for a kit to build a steel boat out of precut pieces packaged and shipped to where ever. Don't think it would be a big enough market to justify the expense of setting up the production cutting and keeping the construction line open.
Radford designs amongst a few others did this with their 'Radius Chine' but your correct the market just isn't there at all.

Frank
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Old 21-06-2013, 22:59   #18
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Re: STEEL HULLS with Composite Superstructure / Topsides

Ive bilt 3 steel boats, one for myself and 2 other boats so far. They were all Colvin plans. We sailed ours for over 25 yrs. She required constance maintaince, but then so do all types of boats Aluminum, wood or glass. I loved the lack of noise from the hull. She was allsteel hull house and deck. Bilding it ourselfs we were able to take time to be sure all surfaces were properly primed and painted. And things were where we wanted them! I sorta feel that bilding your own boat helps ya maintain it ! I always liked the folks I bilt boats for to be around as much as possible so they would KNOW there boats as well as we knew ours! Ive owned boats of every material except for aluminum. If I wasent so old I would be trying to bild one from aluminum cus it's so much easier to work with and you can use much cheaper tools to do the fab work ! The welding of course takes much more practice with aluminum, but it's still doable!! just my 2 cents ( heck my new to me boat is epoxy over a steel frame work ala concrete style ! )
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Old 22-06-2013, 03:29   #19
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Re: STEEL HULLS with Composite Superstructure / Topsides

Decks on a fibreglass boat do not need to be cored. Mine aren't........obviously plusses and minuses to every choice, my choice favoured no wet core over any weight penalty.

I feel that overall fibreglass (with no core!) is the most forgiving for maintenance (and of PO's), especially the deferred kind! - not to say that they are perfect (Osmosis comes to mind!)..........and obviously design and quality of build as important (if not more so) than build material.
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Old 23-06-2013, 10:39   #20
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Decks

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Decks on a fibreglass boat do not need to be cored. Mine aren't........obviously plusses and minuses to every choice, my choice favoured no wet core over any weight penalty.
True, they don't NEED to be cored, but if you are seeking the strongest deck for the least weight, the sandwich cored configuration is one of the best choices. Then it's a question of the best core to use, and I've come to the conclusion that this polypropylene material offers some of the best options for deck use,..including the fact that I get an insulated deck that can be a real plus against solar heating in the vessel.....and it won't rot if it just happens to get some moisture in it.

With proper skins and core thickness it will not require any support beams on the underside....more headroom.
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Old 24-06-2013, 04:47   #21
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Re: STEEL HULLS with Composite Superstructure / Topsides

I have been mucking about in a steel boat for about 27 years now and have just completed a fairly expensive hull refit. All the problems I have had with the hull go back to the numerous water traps built in during the original construction and my propensity to drill holes in the deck and fit things which subsequently leak. I am now of the conclusion that putting stringers in a small steel vessel should be a criminal offense and that frames should be either fully welded or stood of the plating so that paint can get at all places on the plating.

My deck is galvanized 1/8" plate and I have not had too many problems. I have pondered composite construction as an intellectual exercise and have concluded that it is probably not worth the extra effort and expense to do an entire deck however I am beginning to use quiet a bit of aluminum at places where there is a lot of wear and tear such as the for deck where you are handling anchoring equipment and in the cockpit where metal items tend to get dropped etc.

I also now place thin (2mm) aluminum gaskets under any non aluminum items I fix to the deck using a gunk to seal between the alloy and steel. This allows me to remove the items fixed to the deck without damaging the underlying coatings and if water does get under the alloy it acts as an anode and protects the steel.

Steel is an excellent material for the adventurous or paranoid: it's hard to bend, break or burn. Few other boat building materials are as durable provided you can keep the corrosion out of the hull. The underwater bit is easy to protect provided you are careful about not allowing electrical currents wander about through it and ensure the anodes are maintained. I was once responsible for a vessel which had no paint below the water line, relying totally on the anodes to protect the underwater steel surfaces.

One of the things I do like about steel is that it does not burn although the fit out inside generally will.

I I built another monohull it would be steel but incorporate all I have learned about maintenance and internal hull corrosion. I would also go multichine and go with the Van De Statt type building technique. I would also use galvanized plate but regal those places where the zinc is burnt of during welding.
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Old 29-06-2013, 22:09   #22
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Re: Steel Hulls with Composite Superstructure / Topsides

Dear RaymondR, I'll come back and address your posting,...but first let me add this.....
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Old 30-06-2013, 01:07   #23
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Re: Initial Interest in Prefabricated Composite Panels

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Originally Posted by beiland View Post
After quite a bit of reading about PP honeycombs, I'm convinced they made VERY good core material for sandwich construction. And in the 'prefabricated sheet form' they are superior to foam panels, or balsa panels, or plywood, etc.
After actually working hands-on with PP honeycomb cored panels, I KNOW they are inferior to balsa and foam cored panels, in terms of stiffness, strength, and core to laminate bonding.

I wish I'd taken video of just how easily the laminates could be peeled off the core.
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Old 05-07-2013, 23:55   #24
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Steel Preperation & Maintainence

While looking thru a few 'steel hull discussions' I ran across these three references on this one page here:
http://www.boatdesign.net/forums/metal-boat-building/4mm-steel-hull-1930-2.html[/URL]

Quote:
Originally Posted by Wynand N View Post
Jim, If a hull & deck are properly shotblasted (dislike pre-blasted/primed plates) and epoxy coated, especially on the inside after building, there should be no problems as long as preventitive maintenance is done, as is true with other materials as well. I uasually sprayed (airless) the inside with a coaltar epoxy with a minimum thickness of 180 microns after blasted to spec SA2.5.
Older boats, especially home builts were prone to rust, because very few were ever shotblasted in backyards. I've seen some guys using chemicals to remove rust prior to painting,others just wire brushing!! and some just touch up paint on welds etc on pre-primed plates. These are all guaranteed recipes for rust.
Remember, paint is only as good as its preparation. With modern knowhow and epoxy paints it is not neccessary to "build-in" the rust factor. In fact, a well built & epoxied coated steel boat will outlast any fibreglass one.
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Originally Posted by yago View Post
Jim, I have reviewed boats I built over 20 years ago, 4 of my own building and several others built by friends in the same period. They had been all been shotblasted and covered with epoxy paint. Not a spot of rust inside, nothing at all.
On the outside they had a few spots on deck repainted, where the paint had worn off over the years but that was always on welded on eyebolts, cleats etc, fittings that should have been stainless anyway. Hull and Deck were spotless.
Properly blasted and painted, rust is no longer an issue, and certainly not something that you would want to increase plating for these days.
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Originally Posted by Wynand N View Post
.... If your stringers are docked solidly against the plating and the welding sequence carried out as above, you will have no movement between plating and stringer to crack your expensive epoxy.
By the way, after shotblasting to an approx spec SA2.5 (white metal) we sprayed the inside with coal tar epoxy to a thickness of about 140 - 170 micron. Needless to say an airless spray unit was used to elliminate air trapped under paint, especially in corners. Our unit sprayed at about 220 bar pressure on nozzle.
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Old 07-07-2013, 14:03   #25
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Re: Steel Preperation & Maintainence

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Originally Posted by beiland View Post
While looking thru a few 'steel hull discussions' I ran across these three references on this one page here:
http://www.boatdesign.net/forums/metal-boat-building/4mm-steel-hull-1930-2.html[/URL]
Sorry, because of different formatting between forums, that forum link did not turn out correctly.

Here is the proper link:
4mm steel hull - Page 2 - Boat Design Forums


Quote:
Originally Posted by RaymondR
I have been mucking about in a steel boat for about 27 years now and have just completed a fairly expensive hull refit. All the problems I have had with the hull go back to the numerous water traps built in during the original construction and my propensity to drill holes in the deck and fit things which subsequently leak. I am now of the conclusion that putting stringers in a small steel vessel should be a criminal offense and that frames should be either fully welded or stood of the plating so that paint can get at all places on the plating.
...but reading another post on this site, the writer said that " space welded" stringers were the main reason for rust developing as there was no way of completely sealing the "crack" between the hull & stringer.

...needless to say an airless spray unit was used to eliminate air trapped under paint, especially in corners
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Old 07-07-2013, 14:18   #26
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Peel Forces ve Shear Forces

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Originally Posted by 44'cruisingcat View Post
After actually working hands-on with PP honeycomb cored panels, I KNOW they are inferior to balsa and foam cored panels, in terms of stiffness, strength, and core to laminate bonding.

I wish I'd taken video of just how easily the laminates could be peeled off the core.
Peel forces are different than Shear forces.

In general a boats sandwich construction should not experience peel forces to any great degree.
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Old 07-07-2013, 14:49   #27
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Infusion Grade PP Cores & Kelsall Method

As previously stated I wanted to look more closely at the possibilities of utilizing PP cores vs balsa, foams, and other honeycomb materials. I am also looking closely at 'panel construction methods' where these 'panels' are prefabricated to some degree much like the kit-boat builders in NZ and Australia are using. As I look more closely at these prefabricated 'cored panels' I find that they are basically only supplied with a 'basic skin' to which each different builder will have to apply his own additional skin layup to obtain the strength he is seeking. That additional layup is done in free-stream without a mold surface. Therefore it will require additional fairing work to obtan a smooth finish coat. That additional fairing work can be very time consuming.

Contrast that with Derek Kelsall's method of producing his panels ona smooth table, and arriving at a fine finish on the outer surface of his panel. Derek is also almost making exclusive use of resin infusion to build his panels, which makes for a nice uniform panel without resin starvation, and with likely very good bonding between the core and skins.
http://www.kelsall.com/UniqueKSS/WhatIsKSS.pdf

One problem might be that Derek, and several others, insist on using only foam as a core material, particularly sense it stands up under the resin infusion process.

So I'm reading a little more closely and I discover Plascore is now making a "Infusion Grade PP Core"
Infusion Grade PP Honeycomb - PP Honeycomb

Quote:
Utilizing a composite surfacing material, the open cell structure in Infusion Grade PP Honeycomb is sealed, thereby allowing the flow of resin during processing to remain at the bond line with minimal penetration into the honeycomb core. The veil provides a continuous substrate for 100% adhesion to the panel skin material. The core does not incorporate any flow paths, so a careful selection of glass reinforcements that have a resin flow path capability is required. To help facilitate a uniform flow of resin through the sandwich structure, additional pass through holes are added to the honeycomb that pierce the surfacing material at one cell and allow resin flow from top to bottom of the sandwich. Spacing of these holes is typically 4" on center.

Infusion Grade PP Honeycomb features a composite surfacing material that is compatible with most laminating resins.
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Old 09-07-2013, 16:12   #28
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Re: Steel Hulls with Composite Superstructure / Topsides

Brian, thanks for the email about Polyurea Coatings.
I looked over the thread and see different material is being looked at. Hull may be different than deck. These joints / connections should not be an issue for waterproofing with a polyurea product.
The lowest elongation of the polyureas I have seen is around 200 to 400%. Polyureas will adhere to wood, steel, aluminum, fabric, concrete ,etc.
There seems to be one requirement of a substrate for a polyurea to adhere too and that is the ability to have pores or profile for a polyurea to stick t0. So gel-coat is out, but remove the gel-coat and get down to the fabric of a fiberglass and you have a workable situation.
Finding the correct applicator / crew is of a concern. People with Advanced Applicator training from Polyurea Development Ass. or such would be a good start.
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Old 09-07-2013, 16:22   #29
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Re: Steel Hulls with Composite Superstructure / Topsides

O,yes - I have seen videos of fiberglass being mixed with a polyurea spray. Replacing the resins and such.
Polyurea is the name of the Technology - not a product or chemical. There are all kinds of different polyurea chemicals out there. The strongest will be sprayed above 3000 psi and chemical temps from 150 to 180 deg. F.
Also, certain type spray gun makes a stronger finial product. Remember, the spray applicator IS THE MANUFACTURE OF THE FINIAL PRODUCT - so pick your applicators carefully.
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Old 09-07-2013, 18:23   #30
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Polyurea Coatings

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O,yes - I have seen videos of fiberglass being mixed with a polyurea spray. Replacing the resins and such.
Polyurea is the name of the Technology - not a product or chemical. There are all kinds of different polyurea chemicals out there. The strongest will be sprayed above 3000 psi and chemical temps from 150 to 180 deg. F.
Also, certain type spray gun makes a stronger finial product. Remember, the spray applicator IS THE MANUFACTURE OF THE FINIAL PRODUCT - so pick your applicators carefully.
I see that now that there are many variations on this 'product'. I was particularly impressed with some of the videos I had found about the Iraq war delveloped coatings for blast protection/containment.

I found this interesting PFD document:
http://www.huntsman.com/portal/page/...yurethanes.pdf

I think I will have to re-read this a number of times to understand it all. That will have to wait a bit while I develop some other steel hull reinforcing ideas I have in mind to explore.
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