Building Steel Ocean Rowboat - What Gauge?

I would like to build a pseudo, Woodvale design ocean rowboat in sheetmetal. I have the tooling to build, but no boat building experience. I build motorcycle sidecars as a hobby and I'm able to form compound shapes from sheetmetal. My question is what gauge sheetmetal should I use on the hull and deck? My guess is between 14-18ga. I use 16ga on the hoods of my sidecars and I can stand on them without any bending. Weight will be comparable to a wood version. (16ga. is about 80# for a 4x8 sheet.) Boat approx. specs - OAL = 23'6", beam = 6'3". I plan on using a square tubing frame, fresh water ballast. Thank you folks!

 

Intrigueing !

If you care about the weight of the boat, or the noise it will make, or the flotation potential, build it of wood. Since you build side hacks of metal, I suspect that you are an accomplished craftsman. But if you build something like a Monomoy boat or similar, you'll wear out your english wheel and several planishing hammers before you are done. Wood is easier and pound for pound much stronger. Wood has warmth, it does not rust, and it can last for a very long time. (O.K. I confess that it will rot if you dont take reasonable care of it) Finally I think that your boat will have, and retain, more value when built of wood.

I reckon that 16 gauge is satisfactory if you frame it well enough. Well enough means that you will have it supported at least every square foot or so in flatter or modestly bent surfaces. If not it will oil can, make noise, and cause the boat to require more input energy than a more rigid surface would.

Not to rain on your parade here, but sheet metal is not the best maerial for small boats of this sort. If you must use sheet metal, consider aluminum of a thicker gauge. eleven gage aluminum will be something on the order of four times the stiffness of 16 gage steel. The 11 gage alum. will still be lighter than 16 gage steel. It does not deteriorate badly if you use the appropriate alloy. Additional stiffness means that it will not need the extensive framing the steel will require. Aluminum will cost considerably more but it will be worth the difference in price in the long run. All things considered, wood is the best choice in terms of cost, performance, ease of construction, etc.

 

H,

The Dutch build down to dinghy size with steel. Well designed, steel would be the strongest choice by far. Aluminum could be a good route if you have the needed welding skills to work with it.

Steel would be challenging as far as final appearance. That would not be a concern of mine though under the circumstances. I'd rather get there in a rough, workboat looking vessel, than have a yacht proper one sink out from under me from some sort of catastrophic structural failure.

Bulletproof floatation would be critical of course. Wood definetly is preferable in that characteristic.

As to plate thickness, check out Lund's larger aluminum boats to get a ballpark figure. You can then see what a comparitive (strength & other properties) piece of mild steel would need to be gauge wise.

Keep us informed of your choices & progress.

Take care.

TGoz

 

Also check out steelboatbuilder.com. Wynand, a forum member here, has just begun this website.

TGoz

 

I got into a huge fight here with a dutch bloke when I supported the idea of a furniture builder who wanted to make the frame of his experimental dingy out of square-steel-section.

I have had other arguments about using rivits instead of welding to prevent distortion.

I could see that using a lighter guage of steel for the deck would function if you dont need to step on it.

Square section may rust from the inside out and many use rod or bar or angle, however, before I am attacked again I will state - Personally I am all for safe experimentation - you have your material of choice (steel) and if you know the limitations then go for it.

I have seen quite a few discussions about Ocean-row-boats and there are a number of plans being kicked around. Some sort of a plan would make life easier.

The boatdesign member 'solomon grundy' is doing something similar (see the thread below) - he is still discussing his propulsion system.
http://www.boatdesign.net/forums/showthread.php?t=6517&highlight=ocean row boat

 

<b>Steel, wood, fiberglass...lots to think about</b>

Thank you all for your response. I really like to work in steel. My brain is wired for the touch of steel. I gotta tell you...supports every square foot; that's going to add considerable weight, even if I use steel monocoque design. (Formula 1 cars used to be made of glued and pop riveted aluminum). I can see where it will need additional support beyond my initial, conceptual idea. Please view the boat at this site. http://www.atlantix.eu/html/own_des...hip/02_glass_fiber_epoxy_row_boat_design.html
This is the one that makes me lay awake at 3AM. I can replicate this in steel. This "rowboat" is at sea right now and has been for the past 67 days, pushing 2200 miles rowed; A brave young man and a strong willed gal from Hungary.
(oceanrowing.com). Their boat is made of fiberglass and carbon fiber. Aluminum is nice, but difficult to weld. I can Mig or gas fairly well in steel. I can make the additional supports from the same gauge steel as the hull/deck -|_|- or _/\_ ,though tough to curve to fit the hull line. The wood or fiberglass Woodvale designs are under 600# unladen. I'll design the boat on paper, figure in the hull/deck and gussets and let you all know what the approx. weight will be. If too heavy, I may have to dust off the table saw! Thank you for the links to the steel boat builders. I couldn't put it down.

 

Hypmotized, there was a discussion about small steel boats on the forum some time ago. It may be interesting:
http://boatdesign.net/forums/showthread.php?t=8856&highlight=steel

 

Hypmotized: The boat on the site that referenced is most interesting. I could not get much of an idea of what the sections look like. The boat appears to be narrow but not excessively so. The pictures suggest that it is made up of flat sections of material tortured into a suitable shape. If that is the case then building of steel is not prohibitively complex.

I suggest that you make up a flat test panel of about 3 feet square more or less. Then you can experiment with the interior structural arrangement. Load the panels with some sort of weight that will concentrate the load near the center of the individual panels and see what happens. That will get you started without a large outlay of space or money and it will give you some real world idea of just how much of a framework you need. If the panels develope a slight scallop or hollow that goes fore and aft, then that will not harm the boat much if at all. Skin on frame kayaks have that characteistic without apparent detriment. If, however, the scallops go athwartships that will be bad news. Longerons that run fore and aft, spaced according to your best guess or experimental data will probably do the job. The bulkheads or frames should not touch the skin but support the longerons. Plenty of aluminum fishing boats are made this way. If you have a brake you could consider Z sections for the longerons or inverted V or hat sections as you suggest.

I think that you can pull this off and perhaps have a boat that is both unique and functional. We'll be interested in the further developement.

 

Thank you all for the info. Messabout, I'll try to put a test panel together this weekend and park the old chevy on it and see how it fares. I didn't know that the bulkhead should not touch the sheet steel, but only the Longerons. You are right. I believe that's how planes are constructed. My thoughts are that the sheet metal only needs to be welded to the longerons every 6 inches with a bead about an inch long. I've taken apart a few cars and they are pretty much spot welded and it is very difficult to seperate the panels. I went to the site, mullinsboats.com and was very pleased to see some small all steel boats that were built in the early 1900's. Looking at their old pamphlets, their boats were constructed of 18-20 ga galvinized steel, 1 inch lapped and rivited. They seemed to be quite sucessful.

 

One thought on your supports, if you are building a long narrow boat such as the one you posted a link to, it will support itself much better than a wide one and need considerable less of them

 

That makes sense. It's only a 6'3" beam. On my way home from work tonight, I was thinking about just that idea. I took a tour of Schwitzer Aircraft Mfg. in Elmira, NY about a year ago. They make all kinds of aircraft, especially helicopters. I followed their whole manufacturing process for one of their helicopters and I was very impressed. The internal structural supports for the helicopters was thin sheet aluminum, beautifully formed. The fit and finish was a marvel. This technology has been around for some time, but it was great to see a piece of sheet metal get turned into a work of art! I thought of applying the same sheet metal principles to the frame structure on this rowboat, possibly of 16 ga steel. It will take away somewhat from available space in each compartment, but will reduce the weight factor, as compared to angle iron. As it stands right now, if I build the hull entirely from 16 ga.steel, the hull alone, without counting the internal frame, will weigh ~800 lbs. . 18 ga. will weigh ~640 lbs. There is a 17 ga., that will be ~720 lbs. I tend to go with the 17 or 18 gauge, in spite of the weight. I think it has the advantage in the areas of safety and hull intergity. I want to row in the Finger and Great Lakes. Lake Superior is 350 miles long and I would feel better wrapped in a substantial amount of steel, but you gave me encouragement and hope that this thing can become a reality. Thanks.

 

This is the boat that I'd like to build in steel. Stevie Wonder sang of this boat, "Isn't she lovely?"

 

No, he didn't. Maybe you've been hypNotized.
http://www.lyricsfreak.com/s/stevie wonder/isnt she lovely_20131910.html

Anyway, I have a book by Ian Nicolson, 'Small Steel Craft', that has a short description of small Dutch steel prams; "The Dutch boat is of double chine construction, usually of 3mm material but sometimes of 2mm material with an overall length of about 16'. It may have frames (transverse, at about 1' 8") but often does not. It has wood thwarts, but is otherwise all steel." Sam