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boiler size

Posted: Wed Feb 05, 2020 7:17 pm
by lighthousekeeper
Hello recently finished building glen-L fred murphy 30' steel hull tug, for my 8th boat I am planning on going back to steam, building reliable steams (salty) in steel. steam powered. Might stretch it out to 22 feet with the 7' 4" beam. My question is if I build a boiler vft 32 inches high , 20" in diameter with 22 fire tubes 1 1/2" will the boiler be big enough? I had this size in my 21' fantail cedar strip and it was great, but with the added weight of the steel boat, will it do the job? thanks!

Re: boiler size

Posted: Wed Feb 05, 2020 9:43 pm
by DetroiTug
I have a little experience with your proposed project. :D

You don't clarify if the 32" height is the boiler and firebox or not. I'm guessing the boiler as suggested is probably too small. It would run a 3X4 single cylinder double acting or a Stuart 6A, but both of those engines are really too small.

I built the Salty in steel and scaled it up 10% or a factor of 0.1. This brought the length out to 22 foot and the beam to 8 feet. I kept the hull very light with 12 gauge on the bottom and 14 gauge steel up the gunwales. My water leg boiler is 24" diameter, 42" tall with IIRC 24 1-1/2" firetubes. Feeding a 3+3X4 twin cylinder engine. It works and provides ample performance, but wood size and seasoning are important. Green wood makes for a slow trip, but wrist sized, well seasoned wood and shes a lively performer.

I can save you a lot of time and work and searching, if you want one of these ready to go with steel hull and white oak and mahogany wheelhouse, cabins and doors, many antique marine components, crack open the check book and cut me one for 80k USD and you can take her home with you She's sitting on an over rated trailer with dual 5,000 pound axles, new wheels and tires and brakes and lights all the way around, and an electric loading winch :D

I don't really want to sell it, but if someone cranked it up, I would work it in to my plans going forward.


Re: boiler size

Posted: Fri Feb 07, 2020 3:47 pm
by fredrosse
Clarifications requested:

Boiler tubes Outside Diameter = 1.5 inches? Wall thickness = 0.095? Length = 20"?

This is a simple VFT, similar to a Stanley boiler, or a wet firebox type? If a wet firebox type, what is the inside diameter of the firebox and its height?

What is the displacement of the new tug?

Re: boiler size

Posted: Fri Feb 07, 2020 5:49 pm
by lighthousekeeper
Hi, 32 inch in height, 20" in diameter is just the boiler size, I was thinking about a building a square firebox 24 by 24 and 16 inches high. My previous boiler the firebox was small , I found myself stuffing the wood in as much as would fit!

Actually "Iron Chief" has inspired me to build salty in steel, love the double chine hull! I have the frames all welded up at this point I'm planning to build it as a open launch, no cabin. DetroiTug can you give me a estimate on what you hull weighed without cabin, boiler and engine? To me building a boat is all the fun keeps me alive! gives me a reason to jump out of bed in the morning, keeps my brain thinking, planning the next steps, having material, parts ready to proceed without delays it also creates excitement in my neighborhood many folks stop in, some complete strangers but share a love of boats!. DetroiTug I've watched Iron Cheif's video's many times you did an exceptional job! I hope it finds a good home.

Anyway sorry for rambling on, their isn't much more I can do at this point with salty as it will be an outside project today's temp is minus 27 Celsius going to go at it hard late march. here is a video of Fred murphy tug with I launched late last summer still need to dress it up a bit, plan to take it out to lake superior next summer. I put a 1966 318 in her I was very close to making this into a steam boat as it has very close dimensions to the African queen.

Re: boiler size

Posted: Fri Feb 07, 2020 6:04 pm
by lighthousekeeper
Sorry , clarification's on boiler, so boiler 32 inches in height, boiler diameter 20 inches, boiler tubes 1 1/2' outside diameter 22 tubes, and a square firebox 24 by 24 inches 16 inches in height. The plans for salty r pretty advanced and vague to be expected for 70 bucks! haha Here is the specs if built in wood.

Length over all 20'
LWL 18' 4"
Beam 7' 4"
molded form draft 19 3/4"
maximum draft 24 1/2"
displacement at LWL 6200#
center of buoyancy 9' 4"
prismatic coefficiency .622