STEEL HULLS with Composite Superstructure / Topsides

I have heard that marine borer species vary according to latitude i.e. a hull that stays sound in its own back yard will get munched in other locations. Epoxy glass over wooden hull is probably the ultimate but that aint cheap either.

The famous Herreshoff ketch, Ticonderoga, is wood over galvanised steel frame. I saw her for sale a while back real cheap and wondered if corrosion was setting in.

 

No, Ticonderoga is double planked mahogany screwed to bent oak frames, built by Quincy Adams in 1936.

Radiance is a copy of Ticonderoga, of mahogany bolted to steel frames, built by Legendary Yachts and launched in 1996.

 

I stand corrected. Thank you

 

What if?,.... Canal Trawler built in Steel & Composite PP Honeycomb

What if one of the vessel designs I was thinking of building with this 'hybrid method' was something like one of these 'canal trawlers':
1)
or....
2)

Both of these are built for 'canal duty' with steel hulls and hardy rub rails. If you look thru the website for the EuroShip vessels (the first referenced above) you will find quite a lot of construction photos for their canal vessels, and many references to their computer-cut plate kits for hull construction.
http://www.euroshipservices.nl/english/

Their cabin sides and decks are also constructed of steel,.....steel skins with support framing. In order to get 'attachment points' for the finishing walls/skins on the interior surfaces, battens (often wood) need to be installed. Provisions for insulation of the living spaces, provisions for limiting condensation on the inner steel surfaces, etc, need to provided for in the cabin sides, the cabin roofs, the main decks, the interior floors, etc..




What I am proposing is to substitute a ready-made, thick, honeycomb panel of PP. It's already well insulated (trapped air space), limited or non-condensing prone, stiff, with flat surfaces on the interior as well as exterior, to which any number of final finishes could be applied. And these 'finishes' could be glued, screwed directly to the PP panels without other battens, etc. It's even possible that the surfaces of these PP panels could be simply painted, with or without a texture. Or some sort of siding could be glued on. Or some sort of wood laminate......

Some posters have expressed a concern about ship's rigidity without a steel deck. I would suggest that a sub-frame of steels beams could be placed across the ship between gunnels, the PP panel(s) placed over these support frames in lieu of a sheet of steel. Concerns about supporting items / equipments that might be added to these PP decks vs steel decks are probably no more of a concern than the extra support that would be required of the steel deck itself. If the loads are a concern for the PP deck, they would likely be a concern for the sheet steel deck. We are not talking 'work boats/construction barges' here where items are often welded onto the decks, but rather yachts,...... many with teak or synthetic teak decks.(BTW, teak onto steel decks would NOT be highly recommended either).

I actually think this type of construction could be a significant time saver.

 

so the AC 72' are going to made from aluminium next time round coz its stronger and lighter?

 

It looks to lend itself to flat panels for sure. Will the composite panels take some curvature e.g deck and cabin top? Some curvature in the cabin sides would enhance looks too right?

 

Solitary Island catamaran project/example

This Australian company was offering a kit catamaran built using PP honeycomb panels. Note however these were pre-layed-up panels they were supplying, that were pre-cut by computer.....attached PDF.

Regrettable they have had to cest operations for an undetermined time period due to the world economy. Also regrettable they took down some of their very good web pages on their methods, etc

I included a image of the cat,...enough pleasing curves to build the cabins on the canal vessels I think.

 

It would be very similar to the plywood stitch, tape, and glue method, right? Significant additional laying up of composite at stress points would be required I imagine.

 

I built a fleet of CAT workboats using 10mm and 20mm wood veneered PP honeycomb panels and aluminium honeycomb manufactured in Taiwan for partition panelling and cabinet carcases in wheelhouse and berths to keep the weight down.
The panels are very stiff, easy to fix to though I never considered using the material for exterior bulkheads or roofing panels.

 

BIG BANG #1, Lion Whelp's impact test

These two brothers bought an older 65' Alden schooner, and went about restoring and upgrading her. They had a MAJOR concern with hull integrity,

So they built some test panels to do a little investigating. One panel was built to the same layup as the original hull, and another two panels were backed up with 3” thick NidaCore PP. Laying around their boatyard they had some old pieces of railroad track (pretty tough stuff). They picked out a 6 foot long, 157 lb section, and proceeded to drop it onto the test panels, not flat sided, but end on,.....first from 9 feet, then 16',..... and finally 30 Feet......WHAM !!

.....excerpted from an article that appeared in Soundings mag,
Building a Bullet Proof Boat
http://www.soundingsonline.com/boat-shop/on-powerboats/266332-building-a-bulletproof-boat

.....Have a look at some of the photos and the damage here:
Testing the NidaCore
http://www.portlandyacht.com/lionswhelp/construction/chrono/009NidaCoreTest.html


Brian's Note: Not a very 'professional test', but impressive in its own right. Sure speaks to the ductile nature of the PP honeycomb core material. This ductility is a good match for the ductile nature of steel itself.
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…...from that same article,

...hmmm, I wonder if we could eliminate some of the numerous smaller ribs and stringers of the conventional welded-up steel hull and substitute some PP core material bonded to the steel skin??....might save a lot of welding time, and hull plate distortion. IDEA??

 

Short of working alloy or steel plate into compound curves with the likes of an English Wheel scantling are critical because plate essentially curves in mono-profile. This means although a steel hull can look compound curved there will one orientation where it is flat.

Only well designed compound curve hulls can result in elimination of frames and stringers. The easiest way of achieving this is with composite moulds or conventional planking/strip lamination

Eggs don't have internal framing. Bird quills do.

 

didnt Boeing take 30,000kg out of a 400 to make the 747 800 by using composites in areas where its suitable?
I thinks size matters when choosing one material over another

 

I dont see this discussion as claiming which material is best. Each has its advantages and disadvantages. A good designer considers all of these. While I am not an expert I understand carbon fibre has one particular disadvantage: it strains to a certain point then catastrophically shatters. If you are going to hit an immersed shipping container at sea you are better off with a steel or aluminium hull.

Sometimes there are unforeseen disadvantages. During the Falklands War a British naval ship had its aluminium topsides catch fire after a missile strike. Casualties were mostly from burns as I recall.

 

I'm far less knowledgeable than you in boating matters though I am familiar with carbon fiber bicycle frames and components and I completely agree with your reservations.

BTW, as I recall, many Falklands War fatalities were from burning PVC smoke inhalations as PVC was used extensively in at least one of the British ships struck by the French-made missiles.

 

I am not sure of the details but my understanding is that the alloy melted and began to burn also