Steel vs Solid Fiber vs Sandwich

As a newbe, I need to understand the differences between these hull technologies as they affect durability, maintenance, cruising comfort and probably a lot more variables that I cannot think of.

Any help will be very much appreciated!

Have you had any luck using the search function? Google will help you also....

Your asking people to write a book for you. The question is too broad.

Actually, all I am asking is for people to comment on their own experiences, those who have being exposed to the problem. I have read a lot in the net, and all I could find is reports that steel corrodes, but I never got an opinion on other parameters.

Steel rusts, Fiberglas blisters and laminated cores rot. Does that help?

Seriously, if you want to learn more, go to David Pascoes yacht survey site.....

My opinion only. Steel is OK, but you have to stay on top of it to keep corrosion at bay. Cored is OK above the waterline, like for decks, coring material is a consideration, preferably something that doesnt rot because leakage through the deck to the coring material can happen. I would stay away from a cored hull below the waterline for the same reasons as above (just my personal preference even though there is a well respected Brand out there that has a cored hull below the WL where some of them have had to have a peel and repair ). Solid FG is the easiest to maintain, although there can be issues with it as well if the original layup was not good. I have owned wood, steel and FG boats.

I had at least one of each but you forgot Al.
Steel and Al corrode,they require maintenance.
Good foam core is fine (Airex, Corecell, not balsa).
Single skin glass is heavy but no maintenance. Check for blisters before buying.
My ideal material would be heavy single skin below the waterline, no wooden cored stringers or transom, everything above = foam core. The foam sandwich provides great insulation, less condensation, easier to heat and cool.

Wifey B: If you're going for lunch, sandwich.

Steel is for ice breakers, fiberglass is for cruising boats, core is for race boats.

Are you thinking of building a boat? You left out plywood.


https://www.devlinboat.com/wordpress1/2016/03/czarinna-30/

I have thought about this quite a bit in an attempt to rationalize choices I have made. My conclusion is that these are unanswerable questions in light of the dearth of objective evidence available. The advance conclusion for the diatribe that follows is that all boats are poison in regard to your questions, pick your poison and you will do fine with it.

Regarding durability (one of my main reasons for driving steel): Too early to tell is my conclusion though I think there will be a reveal on this question coming over the near term. FRP is a relatively new technology in the history of boat building and there was rapid evolution between solid and cored as well as types of core technology as FRP emerged as a material for boat building. There is a pretty massive number of early FRP boat builds that are turning 30 to 40 years old and we are about to find out if we can sustain their most common points of failure which are related to water intrusion of hull, deck, and house. I am only qualified or interested in buying older boats since I prefer real build quality and the combination of build quality and recent vintage is beyond my tolerance for financial indiscretion. I believe this approach to asset acquisition often leads to valuation after 50 years equal to or greater than valuation at purchase given diligent care. Selection of classic quality of design/material and prideful/expert workmanship is a well proven ownership methodology I think. I like nice stuff and do not care if it is old. Durability is at the top of my list among your questions
During both of my buying experiences over the last decade I surveyed both FRP and steel boats. I experienced survey failures with vaunted brands of FRP boats to include Krogen, Defever, and Californian due to intrusion issues that I was not willing to face. That was not the case with steel. Steel has different issues that I am willing to face and that will vary from individual to individual depending upon prejudice. People always refer to the liability of corrosion in steel. Relentless, uncompromising selection and application of coatings and electrical protection preclude corrosion so your have your choice of spending lots of money and energy to avoid corrosion or same to address corrosion. The former is my choice.
Maintenance: certainly no expert here, but again we are relegated to mostly opinion as there is not a high integrity data pool relating to this question.... so lore is our basis. My assessment is that steel is expensive on a consistent basis to maintain and that FRP gives you some peace early and then failures get really expensive. Over forty years I expect there is not material variation. But, if you are buying thirty year old FRP that has not yet crossed this bridge, perhaps you should consider keeping a very big checkbook handy. It is my view that if I had purchased the 30 year old Krogen that I had a failed survey with, I would have spent an amount equal to the purchase price to deal with intrusion at hull, deck, and house. Not saying that would not be reasonable in terms of value, just not my cup of tea. I like boating better than projects. Some are reverse of that and I really respect them.
Cruising comfort: Probably more related to hull shape than hull material? Any material can be insulated whether inside the sandwich or inside of the hull. I experienced interest dampness which I do not like in most of the FRP boats I looked at but not in the two steel boats that I own. I doubt that was related to build material but more related to insulation, climate type, and heating/cooling need and method. I live in damp cool climate and heat by combustion which is a drying force. In terms of interior sound, I do not own a decibel meter but my boats are quiet.
I have owned and operated metal and FRP watercraft for 40 years and prefer steel. Another individual with the exact same experience could reasonably prefer FRP.
Thus my view that this is not answerable, which view would result in the advice to buy the boat that lights your fire on other issues and not agonize much over this one.

Klee wick, I think I would like steel provided that I could actually inspect at get at the interior of the hull. I would worry about a spot that I can’t see creating erosion issues over time. I have never owned a Al or steel boat, so I have no practical experience.

dhays said:

Klee wick, I think I would like steel provided that I could actually inspect at get at the interior of the hull. I would worry about a spot that I can’t see creating erosion issues over time. I have never owned a Al or steel boat, so I have no practical experience.

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Hi neighbor Dave,
I consider it a common misconception to worry about areas you cannot see in a steel boat unless the designer was a dunderhead. Is not corrosion risk related to longer term exposure to electrolytes or current? If design is adequate, water can only collect to provide exposure in areas designed to collect water. If I can see the bilges and the thru hulls along with pathways for conduits of liquid I am fine. I do not consider that I need to see behind a cabin wall for example. If there is chronic water exposure somewhere, the material covering the steel will point it out to you. Example, if a window leaks, the wood will show you before the steel is at significant risk is my view.
Risk is from the outside where you have completely adequate view. If you have water on the inside of your boat, that is not a steel problem and I think the steel will be fine unless it is seeing chronic exposure which should be hard to miss.
For me, this ignorance had been my bliss so far.
In terms of grounding I think steel is easier than other materials to understand in that regard. You should be completely aware of dissimilar metals in contact with each other to be sure but potential over the hull seems easier to measure with steel and if problematic, the hunt should be straightforward.
Repeat: to each his own.

Great points, thanks. All my experience has been with wood and FRP boats so I am pretty ignorant when it comes to metal boats.

I spent 5 years reading before deciding on my Kadey Krogen.
At the time, if all else was equal, I thought if I could have had my KK in steel, that would be ideal. This belief was in part because:
1. in planning to travel the world, steel is the most abundant and easy to repair.
2. I had looked at a lot of boats in the Netherlands and the Dutch are experts in steel.

Now, after using the Krogen for 5 years, I realize the error of my ways.
James Krogen knew what he was doing.
My KK has a cored GRP hull using some closed cell plastic foam stuff. If it gets wet, it doesn't deteriorate, though if it stays wet, it can cause delamination eventually (as I understand it).
But for me, the positives outweigh the negatives:
Virtually no condensation inside the boat (and that's after being in cold, northern waters for 3 years.
The coring adds buoyancy to the boat
The coring also adds strength AND resiliency to the hull, that came in handy when I hit a few massive objects, one, a submerged rock being unmovable. I was able to spend the next three months and 2,000 nm being oblivious to any damage since I had no water intrusion. (See my blog for details).

So all in all, I'm quite happy with my choices and for my life it's the right choice.
Richard

Thank you all for the very thorough texts.
Another question to my patient forum colleagues: Two Engines or one engine plus a get-home. In my ancient boat education I was instructed that one engine protected by the keel is a better choice, but does it really matter in a boat were the propeller is so deep down located. On the other hand, the old adage: "if you have two, if have one, if you have one you have none."

You will be purchasing a USED boat , so the reputation of the boats assembler is more important than the solid vs cored vs steel theory.

If decks are known to rot , windows leak and the overhead collapse is more of a concern .

Example of solid FRP hull strength.

thete are some glass boats approaching 70 years old from WWII vintage.

steel has proven its merits through the years, but the biggest issue is the interior of yachts...they tend to make simple steel maintenance difficult.

build the interior of a steel yacht right, and its strengths seem to overcome the now lessened weakness of syeel.

but for many, living with dirt and mildew behind cabinetry beats ripping it apart to chase rust.

I spent a lot of time on steel ships and shipyards. Steel is my preference because of its strength. It requires a really good initial painting and proper maintenance. The best is a zinc coating after sandblasting. It lasts just about forever. But steel is more maintenance than fiberglass. It's easier to do a really strong repair in steel, make hull modifications, and so on. Many steel commercial fishing boats get widened or lengthened later in life for larger capacity or a change in fishing methods.
Years ago, in Newport, OR, a large, single screw, steel commercial boat was leaving the harbor and lost steering. The swells caught it near the end of the breakwater and set it stern first on the rocks and then pounded it for 45 minutes before the Coast Guard could get a line to the boat and tow it back in. The rudder was ripped off. The propeller shaft was bent 90°. A lot of hull plating was badly dented and later replaced. But the only leak was where the shaft seal was distorted from the bent shaft. I saw it out of the water.
Wood would have been pieces, fiberglass holed, etc.
Most people don't experience events like that or go to dangerous places. And most owners don't really do proper maintenance on any hull type. So that makes fiberglass the better hull for recreational uses.

Unless you have a technique for forming plates into compound curves, steel hulls are limited in their shape. Can bend plate one way, can bend plate the other way, but not both ways. Unless you press it or heat and beat it. So things like bow flair are not easy to do.

Less labor intensive to build with FG. Once mold is built, a few guys can lay up a hull in a few days and pop it out. But without coring it is heavy, maybe more so than steel.

Cored hulls are very light in comparison, and strong. But a very real downside should water get into the coring.

For a trawler, where weight is not a big concern, my vote is FG.

I think location plays into this also. I’ve spent many an hour grinding or sandblasting steel surfaces and then witnessed flash rust just overnight. That was FL. In NY i dont see that issue due to lower temperatures humidity and lower salt levels.
I can’t imagine the horrors of keeping an older steel boat in the tropics. Especially without inside access to all the plating.

This discussion seems to be built on the premise that you have a choice between cored and solid fiberglass hulls. Not really. Virtually all fiberglass hulls will have coring in the decks, roofs and cabin sides. I don't know of any current production boats that aren't built that way. It would add significant weight to the superstructure if you built it with solid fiberglass.

There are a few builders who core all the way to the keel. Right now I can only think of a few sailboats, like the J/Boats line but maybe also the MJM line of quasi downeasters founded by Bob Johnstone, the same guy who founded J/Boats.

I owned two sailboats with full coring and visited the factory to be assured that it was built right. It was- all through hull penetrations had solid glass around them. Coring below the water line is a bit of a risk- significant impact below can crack the fiberglass and let water inside. But that is a rare enough event and if you inspect it afterwards you will be ok. AFAIK there has never been any waterlogged core in J/Boats.

Coring below the waterline saves some weight and that is important for racing type sailboats, but is irrelevant for a trawler type.

So the real question is metal (steel and aluminum) vs fiberglass cored above the water line and maybe which coring material to use, although 95+% of builders use balsa. There are good and not so good balsa coring techniques, but that is another conversation.

David

dhays said:

Example of solid FRP hull strength.View attachment 73019

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I love that picture of your boat 'on the hard', Dave!

My solid FRP Californian hull turned 40 years old this month! It was the prototype hull #1 for the 34 LRC Californian. No blisters, no rust, no leaks...but keeping her in a covered slip for 16+ years has helped. I have cored decks but they are incredibly thick and solid feeling. I took a hole saw to my forward deck years ago while installing my windlass. I bet the deck is at least 3 inches thick.

The builder told me in a phone conversation several years ago that in 1977, they really didn't know much about FRP manufacturing processes so they overbuilt the boats by a significant margin. "Built like a tank" were his words, IIRC.

I have been very pleased with my FRP experiences with this boat and would never consider another boat in wood, steel or cored hull. But that's just me...

Each material if built well and looked after can offer a wonderful trouble free life.
Each material if built badly, or ignored can be a disaster.
I currently have unpainted aluminium as I use the boat hard and don't like maintenance much.
I have also circumnavigated our wood cored fiberglass yacht which was a fantastic material, light, strong and fast. The trick is to get the correct wood (western red cedar is good) that doesn't rot as that glass will crack eventually, nothing surer.

I like fiberglass since I can do fiberglass work. I don’t have the skills or equipment to maintain steel boats.

I have owned all three and another not mentioned, glass over plywood.

Wood: takes more maintenance IMO. And is susceptible to worms. I bought and sailed an old fishing boat (salt water) till I sold it and I think it is still sailing. But its lots of work all the time.

Glass over wood: I built a33 foot glass over plywood sailboat. I did it right and had no problems till I sold it. The new owner let water collect in the bilge till the wood rotted trough to the fiberglass and shortly thereafter it sank (1,500 pounds of lead keel) in 300 feet of water and was ever recovered.

Steel: I owned a steel 44' Bruce Roberts center cockpit Ketch. Great boat but there were places in the interior where the steel could not be reached for proper maintenance. The rust made me nervous but probably was not a major problem but I did "double plate" the bow because I could not get to it to seal it and the keel was totally inaccessible in the interior which was filled with concrete and punchings. It is now on the shore of a lake in MO with its keel burried in the ground and being used as a lake cabin.

FG: till a year ago, I owned a Gulfstar 36 CC sloop. Fiberglass to the deck. 1" thick on the bottom (had to cut a hole for a speed sensor). Only maintenance I had was the wood on the rails....LOL.

Now I am considering a Mainship 34 because I am tired of maintenance. Yes it takes some, but not like steel and wood.

I wrote an article for "Good Old Boat" (July/August 1999) on this subject. At the time I owned "Millennium Falcon", the BR 44 and loved steel but mainly because you could find welders and scrap steel anywhere in the world, not so fiberglass and good FG technicians. And I was planning a circumnavigation at the time.

I am now too old for the circumnavigation so the FG, close to shore, boat makes sense.

In other words, what is needed is different for different people and different times.

I prefer steel. Due mostly to my decades on steel work boats. It's what I know, what I'm comfortable with, what I trust.

In this thread I'm reading a lot of concern regarding corrosion in inaccessible interior spaces on a steel boat. Pleasure boats may be different because they are by comparison lightly built. But on work boats it has not been a concern. Well maintained, poorly maintained, completely neglected. Interior wastage had never been a problem beyond being unsightly. With two exceptions.

The first exception is under the stuffing box. A constant salt water drip takes it's toll. But that's an accessible space and does not need to by pretty.

The second exception is windows. Many older work boats had rubber channel windows, the salt water gets in behind the rubber and wastes the steel.

Now with modern coatings the interior will be well protected long after I'm gone. And with clamp ring windows the standard that worry is gone as well.

With regard to the exterior finish I am thinking along the lines of a work boat. A durable two part epoxy finish. Skillfully applied is fine with me. When I ding the hull in the locks quick work with a grinder and paint brush and I'm good to go. If you want a glossy finish that looks like the gel coat of a glass boat just popped out of a mold that's another thing entirely. You'll likely pay dearly for keeping that up!

Anyway, back to my first sentence. I prefer steel. But what I can afford is older used fiberglass. As someone else said, the early FG boats were built hell for stout because the strength of the material was not well understood.

What do you folks think about Al?

I have seen a very few pleasure boat “trawlers” made from Al. I don’t mind the appearance of bare Al. I just don’t know what the disadvantages are.

dhays said:

What do you folks think about Al?... I don’t mind the appearance of bare Al. I just don’t know what the disadvantages are.

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1. Wait and ask the guys in Ft. Pierce after they've met me.

2. I'm hoping they don't get to see the appearance of bare Al.

3. No doubt, a few of those guys will be able to answer that question in about a week.

Cheers!