Fiberglass vs Steel Hull they both claim the best

Example of custom steel construction

For reference... this link documents a one of a kind build (there's actually a bunch of pages to run through, and worth doing!). I think these images capture the straight forward nature of the steel construction process. I find the whole thing inspiring and if I had a million to fund a similar adventure I'd be there... alas I have to live in the real world....

Building Ellemaid 1

[Most has been said before, I'll still repeat it in my train of thought.]

As always (and already mentioned) the first question is: What do you want to do? That will restrict you options from the very beginning.
Say for arguments sake something fast for racing (class rules?) VS. selling charters in in the (Ant-)Arctic all year around.


How many do you want to build? One off, small series, large series.
For a single ship metal working is quite competitive.
With CAD and CNC technology metal also works for small series.

Other things to take a closer look at are the actual materials being used:
- For GRP things like which glass or maybe carbon, which core material, continuous core material or small sections to contain water ingress, which resin, vacuum bagging or not...
- For metal questions like which alloy, which welding material, which welding technology, which type of weld, ...
- Which paint system or other protection system and the quality of its application

All of this will change your options, the actual construction, and certainly the cost. - Even after the initial decision for plastic, aluminum or steel.


Do not forget the different skill levels of the builders!

Above Diesel Ducks have a rather simple hull form. I'd say it has been optimized for DIY and little tooling.

Dashews FPB earned their place in the Rouge gallery for their unpainted aluminum look. Still they pull of complex hull shapes using: a CNC cutting table, the indoor crane, a large vertical roll bender and a few chain blocks. Ok, liberal use of bracing too, hard to build an upright frame without it. Given that they don't paint the hulls above the waterline they can't fix fairing problems problems with filler.
They don't have much more tooling but certainly a highly skilled workforce which they can't rush that much. This means a significant investment in payroll, but then a FPB is also a little bit more expensive than a DD, say an order of magnitude.

Hi,

There have been a lot of self build yachts use this technique quite successfully.

A lot I have seen have sported the same flag on the stern and a very similar looking upturned fish bowl in the middle of the deck.

Thanks for that reference. I looked thru it rather quickly, and I will get back with some replies.

I'll get back to answering your questions soon.

Steel Hull, GRP deck and cabin

...successful example from another forum

No racing, no Arctic, just plain old cruising vessels,....two that could venture around the world, including some coral reef areas such as the Pacific islands, and the Caribbean, etc.

As I have already indicated previously, limited small number of units to begin with, particularly in this current economy.

….no carbon, no vacuum bagging (one reason for choosing prefab panels, already bagged)
….no specialty alloys, just good basic ship building steel.
Exercise KISS
….choosing paint systems, and protection systems at this stage is not really necessary to determining the feasibility of steel hulls with composite decks

I am purposely seeking the need for a relatively low-rech work force to be able to put the basic hull, deck, & superstructure together,......part of these reason for 'prefab panels' for the steel & composite parts. This basic hull/superstructure shell would then proceed to a 'finishing group' either in-house or a separate entity chosen by ourselves, or the client, or a subcontractor representing the client.

The idea would be to have a very good quality, standardized basic hull / superstructure product to offer at a very attractive price. Then the individual client would have the option to finish out the vessel to his desire for options, quality, and the budget he wishes to spend on a final finish detail. This 'completion stage' could be accomplished by our own 'independent' finish shop, or any number of other boatyards/ builders.

The purpose of this 'compartmentalization' of the building chores is to maintain the standard hull/shell product in a controlled manner as to price & time frame. Then separate out those building chores that invariable end up costing more for one particular boat vs another because of an individual client's desire to 'customize' his. I have seen these little 'excursions' to satisfy a particular whim end up costing the builder considerable sums of money that they may never recover, and/or are not included in the original quote. These customizations should be borne by that particular client rather than spread out over the range of production.

Brian

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.
Euroship Services, computer en snijservice voor de scheeps- en jachtbouw

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.

Infusion Grade PP Core & Kelsall Method of Panel Construction

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 obtain a smooth finish coat. That additional fairing work can be very time consuming.

Contrast that with Derek Kelsall's method of producing his panels on a 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

Brian, in reference to your earlier post about steel hull building, have you ever looked into Glen L boat designs? In some of their steel boat info the mention a "shrink wrap" building process like you mentioned above. It looks like they do some basic welding at the front and back, then install the bulkheads to hold the steel into position and finish welding once they are installed. Supposedly with that building process, the steel lines up better and requires less fairing. Some people claim that just grinding the welds cleans it up perfectly. Some designs use something similar to the honeycomb panels you mention in your last posts. I only mention them because their site has build pics and some details that you might find interesting or relevant to your research.

Polypropylene Honeycomb Cores

Looks like I'm not the only person sold on this idea for the superstructure of trawlers. Have a look here at what Great Harbor Trawlers has to say

About Great Harbor Trawlers : Design Discussions : Space Age Core

Cold Hard Steel

Just ran across this interesting little article by Bill Parlatore, past editor of PassageMaker magazine



Cold Hard Steel | PassageMaker

Great article. I thought he was going to at some point talk more about aluminun, but he only did as superstructure. So, I'd ask that as a point of conversation too, the advantages and disadvantages of steel vs. aluminum.

Excellent article. My only negative comment is that I am sorry Bill picked CSB for the yard to highlight.

I gave a pros & cons presentation at Trawler Fest this year on hull materials: steel, aluminum, and fiberglass. As part of my research I sent a questionnaire to about 40 of my metal boat owners. One of my questions was if they sold their boat, would the next one be steel or would they consider other materials. Only one client said he would consider other options.

I have dozens of survival stories starting with "if my boat had been fiberglass..."

I attended Judy's lecture and I was astonished at the level of knowledge she possesses on materials.

I've had several yachts and a 30 ft steel trawler over the yrs.
Never had a fire thank the lord. but
sailing between Aust and southern end of Tasmania, crossing the shipping lanes I've twice put a dent in my Below water steel hull.
One was a 2 ft long fairly deeep "graze". First was a DEEP concave. Probably corner of Container as I came down a wave. She came to a sudden BANG. Halt.
halfway down the face and fell of sideways
Threw me off the wheel. Luckily I always sail in Centre Cockpits. Plenty of boat behind me to roll about on.
I could bury my fist up to my wrist in there.
NEITHER leaked.

I just heated both with gas axe. (back home)
Hammered them back out. Faired and repainted.
Sth Aust to Southern Tassie. We in the
38 to 40 deg's where we sail offshore.
Get's a bit bumpy. But with the right yachts it's GREAT sailing. I loved it.
Both of those boats were built in a shipyard by shipwrights for themselves.
5-8 and 12mm Ship steel from the fishing trawlers built there back in '80's.
Plus ALL LEAD ballast, with several 10ltr tine of old OIL based paint poured round them.
. NO concrete and steel ballast in my boats thank you.
I've seen and welded others boats with sides of keels rusted out. "from the insides".
I've also Always ensured I grit blast hull
UP TO waterline every 8 yrs with all boats. Along with changing the Standing rigging.

With the sails, running rig I did every 5 or 6 yrs. Masts when needed.
We do (did) a lot of heavy sailing down there.

When I sold my last 42fter. she was '83, vintage. with below water steel as good day she was launched. Inside and out. ALL surfaces accessable. We blasted her for the sale. 50\50 the $cost.
THAT is the MOST IMPORTANT thing to have with ALL steel vessels.
Access. to all internal surfaces.
Metho stove. NO gas on board. with several solar panels. With a shaft genny, and Walker log for accurate navigation.
If you ever sail alongside a Plastic (glass) yacht in heavy weather, (with very few Heavy... exceptions.)
You glide along through the waves.
The glass ones bounce like corks.
I had ONE. Once.
Actually larger boats in "concrete". are some of the most comfortable heavy weather hulls you can go to sea in. Just don't bounce off anything.
45 ish yrs ago I tied off alongside a wharf in a little 32ft Concrete I had.
Woke up early in morn. with a wharf 6inch timber sawing back and forth above my head. In and out the hole it had punched through side of boat hull.
Luckily ABOVE waterline. Easy to fix though.

PLUS. If going offshore with a meduim sized boat.
Have a heavy truck tarp. rolled, on board.
with lead? weights to tie along centre line lengthways. and long ropes along both sides.
You get a leak..
Feed it down over bow let centre drop below keel. feed it back along hull past point of leak. than pull it up to sides of boat.
Water pressure will hold it over hole and maybe give chance to do some repairs.
I always carried 3 battery's. accessible. some cables and clamp\holder. to weld with.
Scrap pieces of steel. (Light will do) and a coupla big hammers.
Tubes of silicon. and a Battery drill with self tapper long stainless screws. With a coupla "Acrow Jacks" for bracing.

I'm 75. Old school. Brought up on timber Yachts and fishing boats.
Spent many a day recaulking seams. At sea and on rollers on beach.
The next yacht I sail back with one hand on tiller and t'other bailing. Won't be the first.

You think about it "firstly". b4 going to sea. You can keep virtually any boat afloat long enuff to effect repairs. Even when you spring a stem plank below water.
I did once in a 28fter. and I've done 90+ % of my sailing by myself.

Unless you get a BIG hole or complete collapse of something serious.Where there's a will. There's a way.

Get hold of some old British navy. "Vessel Maintenance and repairs at sea" manuals from library if you can.
They used to put holes in side of their "SHIPS". to list them and repair while at sea.
I've gone over side recaulking a below water plank in my time.
Lowered down on a rope with 3\4 hose in gob to suck on.
Not in my '70's though.

We used to have some bloody good fun in those days.
Not like these all one piece moulded, welded hulls nowadays. Boooring.
BUT much safer hey.

Aluminum is a lot lighter. Steel has stronger puncture resistance

My post as was the others in this thread was over 4 years ago....

Thanks for sharing your years of experience, it is much appreciated, lots to learn from those with many miles under their keels.