building a 25 ft Tug

Hey PDW- In Toms book he mentions for a 40 ft boat that 1000 lbs of weldment is needed if using arc. did i misread that??..thats about 3000.00 (U.s)!! is it that expensive? how much for a 25 ft boat would it be 1/2 that?
how much do you figure on spending on weldment for your boat?

 

Difficult to be sure as I had a lot of rods to start with. I am on my 4th 12.5 kg box of 2.5mm E4311 rods though and I've used maybe another 20 kg of other rods like E7024. Now I've switched to MIG and I'm about through a 15 kg roll of 0.9mm wire, used maybe 5kg of flux cored wire as well. Probably burn up at least 1 more 15kg roll of MIG wire plus some stainless rods/wire. That can get really expensive, a 5kg roll of 309 wire for A36 to stainless welding is nearly $200 locally as opposed to $32 for a 15kg roll of steel wire. Fortunately I have about 40kg of stainless stick welding rods that a friend of mine scored at an auction. I paid him $50 for the lot!

I think 500kg is a bit much but 150kg or more is quite feasible. I buy my consumables from a welding supply place and get a good discount off of retail. With these sorts of quantities it's worth asking.

Money-wise I'd say I'm going to spend at least $2000 before I'm done. A 4m3 bottle of argon/CO2 mix for the MIG seems to be over $100 now so what I save in wire over using E4311 rods I lose in gas costs. OTOH I save on grinding disks and time.

You'd better budget on using maybe 200 of the 125mm grinding disks and a like number of the 1mm cutting disks too. Maybe you won't use that many but you'd better plan for it. I buy mine in packs of 25 or 50.

The costs do add up but at least you don't need to buy the consumables all at once. Here also Ebay can be your friend for some stuff though I can buy MIG wire cheaper from my local welding supplier than off of Ebay. I bought my new MIG off of Ebay and am very happy with it.

Can I depress you over costs any further? Sorry but the bits & pieces do add up fast. I've been through a ton of plasma cutting tips too, for example, worn out 3 pairs of overalls, destroyed steel capped safety shoes, welding gauntlets, riggers gloves, protective glasses etc etc .....

The bright side is, I've now fitted the last of my bottom plates and I've more than half of the deck plated as well.

BTW don't take the plating sequence as outlined in Tom's book as gospel for all cases. It applies to that pinky hull form specifically. I am using a different plating sequence for my hull based on Tom's advice. It has worked very well.

PDW

 

Thanks PDW-- im going to add some positive feedback since i appreciate your help--It's all good--any boat is going to cost a fair bit of money--i just want to make sure i dont over extend myself when i get going--the advantage of course is i dont owe a bank money or interest..and i have lots of time...much appreciated--wow your really coming along with your project--this is inspirational for us just starting--i hear a lot about failed projects and i DO NOT want to be a statistic..so i am checking it out...is your boat round bilge??.Colvins gazelle i think is mulit chine--but I wondered why he didnt just use a round bilge for that hull- and the wine glas shaped hull in his book, confused me since i thought that was the pinky he was referring to might be the gazelle..?

is there some advanatage to double chine over round bilge??..
i liked all the round bilge hulls ive seen especially the dudley dix designs...although im a powerboat guy--he does use round bilge in his echo 38..nice design...
I was looking at Colvins site and was trying to find your design...
I sure wish he designed some tugs to view...sigh...

 

Don't know your plan or hull shape, but gravity works for free, if you pull the bottom plates up after sandblasting and prime. A little thought along these lines can save quite a few man hours of cleaning.

Ron

 

The Gazelle is single chine. So is the Saugeen Witch I'm building - you'll find it under Tom's medium displacement sailboat designs.

I'm attaching a couple of pix of Gazelle hulls I've collected in the past. One was close to me and I often think that I probably should have bought it. I had good reasons for not doing it at the time though. The other one was for sale in another state, never been in the water though 20 years old, but asking far too much money.

The pinky schooner in Tom's book is a double chine hull form with raised foredeck and a pile of other tricky features. It's used to demonstrate how you go about various tasks in building a boat and there is sufficient detail to build one from the book, with Tom's permission. He won't answer any questions about it though if you haven't paid his fee which is more than reasonable. I don't answer emails from people who use my software unless I'm getting paid either.

Advantage of double chine over round bilge? Ease of plating, that's it IMO. Scale of difficulty in building is single chine, multi-chine, radius chine (maybe, dunno) then round bilge. Same amount of material but the time goes up a lot, so does skill & equipment needed though maybe not so much if the whole boat can be cut from a CNC kit.

I like building stuff so this project is entertainment for me. When I've finished it I'll sail it for a while and consider building another one. As long as I don't lose too much money on the materials (labour I consider a 100% loss) I'll be quite content. Alternatively I'm going to have a massive garage sale....

PDW

 

Those hulls look nice from the pics--funny when you look at a 40 ft'er out of the water-it looks huge--but when your on it and in the water--it seems to shrink especially when youve been on it for a day or two...
The Gazelle is a nice design. I think it was Klingel that built a couple powerboats. Not many others have really written about powerboats done in steel. there are NONE (no books) for tugs. sadly--i think many people would build a character tug if the knowledge was out there. I know its basically the same as any other metal hull, but there are some unique differences. for example trying to design a boat that can accomodate 350 hp in 26 ft and having a 36 inch or more prop demands a lot of expertise. round bilge hulls are great for a tug- but radius chined hulls are difficult to design for a tug since they arent constant radiused. I tinker in design. But find it hard to design a good tugboat- if i could id just use my own design...but its too hard for me--im not an N.A.
this little tug im building is very nice for pushing houseboats and the like.

where do you plan on taking your boat?..sounds like your build is going quite fast too! Its winter here now and the grond is solid. so ill have to settle for making the frames over the winter and setting them up in the spring around May...
the boats ive seen for sale--were bare hulls- and i could have built one for the price they were asking and then some! and they werent what i wnated--i think a large part of why people build is because they get more of what they want. im very picky about designs...i sometimes get caught into the perfetc boat syndrome- but ill settle for 90% of what i want...(jokingly)

 

I'm planning on going as far as Bruny Island in my boat. Given where I live that's very much an in-joke I'm afraid. After I achieve my plan, who knows? I may work up to going to Maria Island in time. I spent over 15 years stooging about in ORV's and an icebreaker going where I was sent and never being able to stay to poke about interesting places.

Unfinished boats - hard to say. I've seen a couple of quite reasonable buys but mostly the people have a greatly inflated sense of what they're worth. My opinion is that until the boat is in the water and usable then its value is based on the difference between scrap and the cost of buying one ready to go minus the cost of the missing bits. This renders some hulls of negative value; I declined to take one for free and I know where I could get another for the value of the lead in its keel. Still too expensive.

I thought you were going to get everything CNC plasma (or laser, whatever) cut? If you're going to make the frames yourself and then use CNC cut plates you'd better be obsessive about getting the frames within no more than 2mm error and symmetrical. Cross brace them with angle iron while the frames are still on the welding platen and don't skimp on it. I used 30x3 angle iron and it isn't stiff enough but I didn't put on diagonals, only a vertical on the CL and 2 horizontal braces, one at the DWL and one higher up. I have some minor distortion which I can work around as I template my hull panels off of my as-built frames. Most of mine are spot on so I can use the stbd side template for the port side plate but I always check.

If I built another hull I could take at least a month off of my time, maybe 2. You have to pay your dues regardless of book learning. Part of that is all the infrastructure I've built up. The other winter job for you is to build a decent sized gantry to lift bits up. You really can't do without one. Even with CNC cut plates you'll need to handle 200kg bits of steel or heavier. I have some ideas for a plate rack next to my cutting table if I built another boat.

PDW

 

Hi Pdw-Ill look up those places since they arent familiar to me--ahhh but to sail aweigh-its like free energy(almost)!

yes--i still want to get the cnc files for that design-mostly just for the frames- ill probably just plate it myself without plate cut sections
what happened was--i was in touch with the designer(or his staff)and they didnt have the cnc files available-but told me to wait for a while and see..but I dont really want to wait...i was very disappointed. so im still waiting to hear from the designer about those cnc files.
I could do some other things too like build the rudder- I thought about a "floating" strongback -like glen-l's fred murphy- that boat is set up using a wooden strongback. i think also ill build her upside down. I was looking at Wynands site-he is (was) a metal boatbuilder, and i read over his site. he likes the dudley dix designs. he uses a simple steel strongback as well...he builds his boats inverted. I like this for a few reasons...one being that since my boat has an almost flat bottom it makes the welding easier. also its small enough to right easily. i cna keep her a little lower to the ground too...

yes i have some steel i bought from a local farmer that was used in some trusses from a barn. Ill be making the lifting gantry hopefully in the next two weeks...which reminds me I gotta call him to see when the steel is coming...
ill use two a frames with a cross spall. similar to Murielle's.

The following two pics are both tug designs...
the first is called the Echo(Dudley Dix)38 ft loa
the second is the Fred Murphy(Glen-L)26 ft loa
this seems a very good way of setting up the building ways...

 

Doesn't matter which way you build in the end so do it how you think will work best for you.

If you're going to cut your own plate another thing worth having is a table to do it on. I've attached a photo of mine. Basically it's a frame made of 40 x 40 x 2.5 RHS with 30 x 3 angle welded across it. Dimensions 3000 x 1800 because that's the biggest plate size I'm handling. It's actually a bit lightweight but a centre brace and some short diagonals would stiffen it up nicely. I made the height 750mm off ground level IIRC. Castor wheels one end so I can roll it about when there's no plate on it. It doesn't look very pretty any more.

Make one out of whatever you can find. If you need to make your own frames from flat bar then some ply or compressed chipboard flooring attached to the top will make a fine platen for drawing out the frames.

Start looking for a plasma cutter if you don't have one. It'll be far more useful than oxy-acetylene cutting gear and I have both so I speak from experience. A 50A plasma cutter with a small air compressor will work fine for cutting 6mm plate and it will cut 10mm plate in my experience.

Scrounge all the angle iron, flat bar, RHS etc that you can. Also keep an eye out for some heavy stainless for your prop shaft, it's amazing what comes up. I bought 2m of 50mm OD 316 stainless round bar for $50 and I don't really have a use for it.

 

pics of my own 27 ft design

 

Looks nice.

But why a mix of radius and hard chine? (at least thats what it looks like to me )

L

 

Hi Lurvio!!...this is the roughed out version...here is the corrected one--it has a huge prop aperture- about 44 inches..so the design was difficult to get clean transitions between the bow and stern in order to make the plating simplified so i believe this is why there is kind of a hybrid chine style to it...

 

and the hard chine version

 

If you are a decent welder I would stick with an E7018 rod. It is a little harder to use for a rookie but once you get the hang of it the weld is superior.

Scott
Fab Manager
Welders360.com

 

I've been busy lately with some metalwork (woodchip heating system) and have welded maybe 50 sticks of OK48.00 (your E7018) in both 2,0 and 2,5mm. The brands are Esab and Lincoln Electric (Würth), both quality products, the latter is maybe a little easier to start with. My cataloque (Esab) does not even recognize E6011, closest is 46.00 (E6013) which I have very little experience of. By data comparison the 48.00 makes a better weld and lasts longer per stick. My dad has been welding his whole life and he always uses 48.00 sticks. He's done some mayor machinery (including a circular saw mill from 1980 that still beats most factory made opponents in speed) and they have held together so far.

I learned welding (in a school about ten years ago) with OK63.30 (Stainless - 316-L) which is a bit easier to get started with. The slag basically falls off itself. I have never bought these so I don't have any idea about price differences.

About price, I had to buy 3,25mm OK48.00 sticks couple of years ago, the local agricultural/builders shop had Wallius 10kg box with a pricetag of 72€ on it. That seemed a bit high so I called the nearest Würth dealer and asked for their price, 22€ for the same size box. Easy decision to drive to the next town.

An old friend of dad's recently retired and he brought us a big bunch of sticks and said he'll bring more. Needles to say, I won't be shopping for OK48.00 or OK63.30 anytime soon. There was some special sticks, some of which are yet to be identified. The most interesting is an Avesta Welding product, 5mm greenish gray stick that only has a print "ref-A 1160" in the center. If anyone of you recognize them, give me a shout.

BTW, If I had one, I'd use a Mig-welder, but sticks work fine for now. The welder is a 220A Kemppi rectifier (?) machine.


Seems like another unfiltered brainfart of mine.
Lurvio