Aluminum dory skiff

[Rusty Bucket]

Hi Everybody, Here are some pictures of the dory skiff I'm pecking away at. She's a plan by Glen L. Whitt called Hunky Dory, aluminum version. She's 25' long by 8' wide out of 3/16 5052, 3/16x2.5x2.5 6061 t-6 angle for frames, 1/4x1.5 angle bottom longitudinals and 1/4x1.5 flat bar side logitudinals. This boat is a piece of cake to build so I would recommend it to anyone. I stretched the boat 3' and changed the framing schedule so that I could use whats commonly available in my neighborhood. The gunnels are clear pressure treated pine 1x1's laminated with polyurethane glue and stainless steel sq. drive screws. The transom is laminated 3/4 p.t. plywood sandwiched between 3/16 inner and outer aluminum sheet. I intend to use it for a nearshore 6-pack business when I retire. I'm power it with a yamaha 115 or a honda 90 depending on who gives me the best deal. regards, rusty

[Bob S.]

Nice looking project. Why the wood details?

[Rusty Bucket]

Thanks for the compliment Bob, I'm putting the wood details on the boat becouse I love the look and feel of wood. I really like the feel of a wood deck under my feet and the way it looks. I just turned 57 last month and I've spent my whole adult life building things out of metal or wood and I really appreciate the various properties of both, to combine the two just seems natural to me. I remember working on this ocean going tug boat back in about1972, I think she was called the "Mary Coppege", and she had the most beautiful walnut captains cabin in the middle of all that steel. Just stuck with me I guess:) Thanks again, rusty

[Bob S.]

Rusty, I looked at that plan on the Glen-L site and they show a motor well option. Was wondering what you thought of that and why you chose a transom mount o/b.

[dick stave]

Nice looking dory skiff,Rusty,I like the wood details.I currently run a 15'6" dory with a 4 stroke Yamaha jet and opted for a wood deck as well .Its light ,provides good traction,and removeable to get under there a couple of times a year with the pressure washer and clean out the silt and beer caps...

[Rusty Bucket]

I chose the conventional transom mount for the outboard becouse it's quite a bit easier to build, saves room in the cockpit and nets are banned in Fla., although some crabbers are still using the old trembly mullet skiffs. I'll most likely build a cover over the motor to serve as a sort of poling platform, although I doubt I'll be doing a lot of poling. I seriously considered a Hamilton Jet setup but the Rep. from hamilton talked me out of it, said they didnt work well on a flat bottom. I would appreciate any input about the jet setup, this boat has a fairly narrow flat bottom, not like a jon boat. The wood thing with the laminated P.T. comes from my contractor business where I handle a lot of really nice wood and dream of how I could use it in a boat, I'll use it to build a faux teak deck and see how it comes out. Check out the pictures, regards rusty

[timgoz]

Nice looking job Rusty.

TGoz

[Bob S.]

Well an inboard jet works better with a bit of a v bottom but if its jet power you want for working the skinny water then by all means you should consider a jet outboard. Very common up here in the PacNW for running the rivers. The shoe (suction box) runs about even with the boat bottom so whatever you draw you can run in.

http://www.yamaha-motor.ca/cached/scale0.5.products.images.outboards.img_F115JetDrive.jpg

[Rusty Bucket]

Hi Timgoz, I see you're a machinist, I used to run a really nice prototype shop that had some basic NC machines and a sweet welding department. I can do the basics but things like cutting gears and broaching and stuff like that are beyond me. Are you an inside or outside machinist? .... Hey Bob, the jet motor is definitely a possibility. Is it true that you need twice the horsepower for the same performance as a prop setup, and how big do they make them? Around here we have these grass flats with this floating wire like grass that tends to clog the foot on the jet motors, some people are willing to put up with it and some arn't so you get a lot of conflicting opinions. I'm happy in three feet of water and this boat is pretty big for the truly skinny stuff. Regards, rusty

[Bob S.]

I believe you de-rate the motor by 30%. For instance a 115 Yam is equiv to 80 hp if you buy it in the jet format. Sizewise I've seen guys put aftermarket jet units on 200 horse tiller motors so sky is the limit I guess. Not sure about the grass, around here they suck river rocks which can cause some premature wear.

[timgoz]

Rusty,

I work at a specialty steel company mainly on petrochemical fittings & centrifically cast tube. Alot of time on VTL's and pull-bar boring machines. Some lathe & conventional mills, radial arm drill machines, ect... Usually we have pretty loose tolerances, which is good as most of our machines are ancient. They do the job though. I have not touched CNC since machinist school- and then barely. That was some time back.

I really like how you did your gunwales. Are you going to fit aluminum over the motor cutout and/or epoxy saturate the exposed ply?

TGoz

[Rusty Bucket]

Hi tgoz, Thanks, I'm not sure yet exactly how I'll build over the engine, I think I'll wait to get the engine in place and consider clearences and such. The new four strokes are pretty quiet and don't look bad so I may leave it open. Have you heard anything about the new evinrude E-tec motors, are they any good ? I have three outboard motors now and I couldn't say much about them except that the little yamaha 25 seems to be bulletproof. The other two are mercs and I've put 2 stators in the 60 bigfoot which means you get towed to the house. I actually prefer straight inboard with wet exaust systems, gas is ok with me. This boat I'm working on now really dosen't lend itself to a straight inboard, too many hard oyster bars inshore. If you've read D. Gerr's " the nature of boats" you'll see what he calls a mullet skiff thats about 36' long that intrigues me, tried to call him to see if he has plans for aluminum, couldn't reach him. This boat I'm building now is sort of a trial run to develope some ideas for a little bigger boat later. Gotta eat, later, rusty

[timgoz]

Rusty,

Last I knew Gerr was running Westlawn Design Institute. You may be able to reach him there. I have his book. IF I can locate it I'll check out the Mullet.

I do not know of the new Evinrudes. My outboard experiences are in the 25hp and down range. A 9.8hp 2-stroke Nissan in Alaska in 2003, gave me good service.

Back in 1991 I was attending Chapman's School of Seamanship in Stuart Florida. We would do boat handling out on the Indian River. This was also where Evinrude ran there test boats- balls to the wall! I can attest to the fact that they worked those motors. Our largest boat at the school was the Chappy. She was a 48' twin inboard diesel which had been donated to the school by Evinrude's widow, "Francis Langford Evinrude. Just a little trivia.

Take care.

TGoz

[Rusty Bucket]

Hi all, Im going to Tennessee for a week so I'm going to be off the grid, got some hay that needs fertilizer, will look forward to reading the posts when I get back. rusty

[fishface]

Rusty,

Is it OK to put PT lumber in an aluminum boat? These threads scare me:

http://www.boatdesign.net/forums/showthread.php?t=11541

http://www.stripersonline.com/surftalk/showthread.php?t=520807

http://groups.google.com/group/rec.outdoors.fishing/browse_thread/thread/11cc3bde60644379/8844d7e83821d04c%238844d7e83821d04c

John "fishface" Thomas

[Rusty Bucket]

Hi John, thanks for the heads up about potential corrosion problems that might arise if you combine pt wood and aluminum. It got my attention so I went out and looked at a 20' jon boat that I owned for about five years and sold to a friend. The boat was new in 1979 and has been sitting on a aluminum float on trailer with 4x6 pt bunks covered in poly carpet. The bunks are screwed directly to the aluminum h-beam. I rebuilt the trailer when I got the boat and found no damage to either the trailer or boat although the axel was pretty much gone. It seems that 27 years would be enough time for the " pt to eat the aluminum like candy" but it didn't. I enjoyed the links you led me to. I think the transom damage was text book example of stray current electrolysis, that outboard is nothing more than a big generator and I'm guessing that the problem lies in the grounding to the aluminum hull. The hull corroding adjacent to the pt bunks on the other boat I can't explain, I would love to see pictures. I put together a little experiment just for the fun of it, maybe I'll learn somthing. It's a 5 gal bucket full of salt water, into the salt water I put a piece of 3/16 alum. screwed to a piece of pt plywood with ss screws, see picture. I'll pull it out once a week a take a look, let's see what happens, Regards, rusty

[fishface]

Rusty, Thanks for the informative reply! As a "store-bought" aluminum boat owner, I've not had any corrosion problems, but I keep my tin boat well rinsed off after a dunk in the salt. I had heard of people bottom painting their aluminum boats with paints that contain copper and having problems but it's all hearsay. I'm not a chemist, but I'm hoping for a long life for my aluminum fishing partner so I thought that I should pass those posts along in case they're based on fact. I look forward to reading more about your experiment, and your beautiful project. Nice Work!

John T.

[Rusty Bucket]

Hey John, Thanks for the reply. I want you to know that I'm not totally convinced that Pt wood dosen't have a corrosive effect on aluminum, that's why I'm doing the experiment. My experience and intuition tell me that people are jumping to conclusions about a subject that can be pretty complicated and might not always result from the obvious. I'll let you know how the experiment goes. regards,rusty I posted the first part of this reply this morning, now it's late afternoon and I spent an hour or so doing research. I'm a contractor and this morning I got a unit of pt 2x8"s in and pulled one of the tags off the end of a board. It says on the tag not to use it in direct contact with aluminum! All the treaters say the same thing about acq treated wood, they go out of their way to say don't use it in contact with aluminum. I wondered why I'm not seeing a problem when I've used aluminum on stall doors, bar grates and other things I hang on AG structures I build. It's not the copper in the treatment that causes the problems but instead it's the alkalinity in the acq. ACQ does contain more copper than traditional cca treated wood and that might not help. Pressure treated plywood is still treated the old fashioned way--with CCA. I wondered why the plywood/aluminum experiment wasn't even showing discoloration after a 5 days in salt water, I think I have the answer but I'm going to do a parallel test using a piece of 2x8 which I know to be ACQ. In any case I'm going to lay off the ACQ. Thanks for drawing it to my attention, I've learned a lot and hope this whole thing isn't too boring. regards, rusty

[fishface]

Rusty, Please let us know what you find out. It's not boring at all.

John T.

[Rusty Bucket]

Hey everybody, It's been 3 weeks since I started the experiment to try and create corrosion between a piece of 3/16 5052 plate and a piece of 3/4 acq p.t. plywood placed in a bucket of salt seawater. The piece of 3/4 p.t. dosen't seem to have much appetite for the aluminum. If you look at the contact surface between the two you can't hardly tell they have been screwed together, only the faint outline and a very light stain that wipes off with a finger, the shine is still on the aluminum. If you close your eyes and rub the surface you can't feel any texture. What was interesting though was the condition of the stainless steel screws I used to stick the two together. The day after I started the test I noticed that the heads of the screws had turned from a typical shiney ss look to a dull grey. When I removed the screws to have a look one broke off and showed a rust stain a the point of failure. The other screw came out but the part that was in the pt plywood was dark grey almost black. The approx. 1/2 inch sticking through the back side of the p.t. was normal looking. see picture, regards rusty

[Rusty Bucket]

Here's the pictures of alxpt

[dick stave]

Hey Rusty,
Google "nobility of metals". There is a galvanic series of all metals (a pecking order if you will ) and it just so happens aluminum and copper are mortal enemies.Aluminum being the loser. If you want to wreck an aluminum boat , throw a handfull of pennies in the bilge.

[Rusty Bucket]

Hi Dick, I appreciate your heads up about the tables of nobility relating to metals. I have to admit I'm pretty familiar with them. I would absolutely love to see some pictures of these two metals locked in mortal combat. There is a direct relationship between the size of the anodic metal and the more noble metal. Did you know for instance that common alloys 5052 and 6061 aluminum can and often do contain up to 10% copper, Do you have any first hand experience with a hand full of pennies destroying an aluminum boat? regards, rusty

[openboater]

Rusty, how about an update. Is the boat in the water yet? What does it weigh w/o motor. how's it handle at low speeds, high speed ?

[Rusty Bucket]

Hey OpenBoater, thanks for the inquiry. I haven't done much to the boat since I got back from Tennessee. This is a really busy time of the year for me so I don't often get to do what I want to. The questions Relating to P.T. wood and it's effects on aluminum kind of stalled me out there for a few weeks, I wanted to find out for sure whether I wasn't doing somthing I would regret down the road. Your interest in my project and the pictures of a pretty little wood boat in the wood boat forum inspired me to go out and work on my boat for a few hours yesterday, it felt good, thanks! I spent yesterday removing the 2x2 pt cleats I had screwed to the vertical legs of the floor frames. I put a layer of plastic sill seal between the cleats and the al. angle, a little isolation just to be on the safe side. I'll screw the deck boards to these cleats. I'll lay 2.5 in. of foam sheet between the top of the longitudinals and the underside of the deck boards, this will give me 1.5 in. of space for a "bilge" to let water flow bow to stern. I'll do same to the sides. I'll post pictures as soon as I reach that point. Thanks again, rusty

[bgeddes]

Nice looking craft Rusty!! I'm in the first stages of building a small aluminum 'weekender' houseboat in aluminum. Very similar in size to your Dory. I have some plans from an old magazine that use wood, but I have very little knowledge of wood. After spending 10 years of my life working on aircraft, I am more than familiar with aluminum. I have a couple of questions reguarding your beautiful boat. First question is about alloys. You used some 6061, typically an 'aircraft' alloy, was availabilty your deciding factor? For my boat I was planning 50xx alloys and TIG welding for bonding. Can you tell me what holds it all together? From the pics it looks welded and I was curious about the technique.

Thanks again, can't wait to see your Dory afloat.

[Rusty Bucket]

Hey bgeddes, Thanks for the nice comments about my boat. You were right on about my reasons for selecting the more commonly available alloys for building my boat. In my part of the world the metal wholesalers don't stock and have almost no demand for the 5086 alloys. They would special order them for me but since I was going to buy as I build I didn't think that would be practical. Most of the "gurus'" on the subject say that 5052 and 6061 will work fine for an aluminum boat which I agree with. My background is in steel shipfitting and fiberglass production boatbuilding, this is the first aluminum boat for me and the smallest metal boat. This boat is welded together using a Hobart (miller) 250 amp mig welder and a spool gun. The shape was probably plywood to begin with and reworked for aluminum, I used the plans to create a set of offsets and station spacing and winged it the rest of the way. Good luck with your [project, Rusty