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Power Drifter Project

Posted by RedwoodRob 
Power Drifter Project
January 10, 2012 08:23AM
Hi everyone,

I'm brand new to the forum and boat building and was wondering if I may be able to tap into the knowledge of the forum members about construction materials and methods to suit my project.

I want to build a jet sled with something lighter and more durable than plywood/glass and was wondering if the PP honeycomb could be used in place of a marine plywood hull and sides, but encapsulated the same way. One thing I am totally unsure of is thicknesses of material needed on the hull, sides, and transom.

The boat I'm interested in building is about 18-20ft power drifter style boat, I will attach a picture. The one in the picture I believe is a stitch and glue plywood/glass.

I have a garadge to work in that is big enough for the boat, and I'm a carpenter by trade so I'd like to think I'm handy enough to do this, though one thing that makes me wonder if I should is cost. I have no idea how much materials for something like this would be, can you give any idea? Costs may be a hang up for me.

Thanks for any help,

Rob




Re: Power Drifter Project
January 10, 2012 03:43PM
Search the forum archives, several people on here (Larry Hedrick for one) have built successful boats using honeycomb panels for the bottom, sides, bulkheads, decks, etc. The material has it's issues, but can be laminated and worked the same way as plywood, so it makes a good substitute. It costs about twice as much per sq ft as marine plywood. And not all honeycomb panels are created equally - see my post on materials durability.

Right now I am building a 16'9" plwood dory with a plascore bottom. I will spend aprox 3500-4000 on materials. With the sled, you will (obviously) need an outboard too, and those aint cheap.

Jeremy Christensen
Re: Power Drifter Project
January 10, 2012 05:08PM
The photo is almost exactly what I have been looking for.
After a lot of thinking, there are many things about the Rapid Robert design which don't make sense to me. When I start to change the design to what I think makes sense, it turns into the boat in your picture but with higher sides going forward.

Honeycomb will make a much lighter version then plywood.

Do you know how much horse power is on the back of the boat in your photo?

Check out this image

http://www.woodenboatpeople.com/photo/hunky-dorey?context=user

The boat is designed by Don Wakefield and built around a Yamaha wave runner image.

All of the high power jet boats are aluminum. I can't say if Kevlar/glass honeycomb is suitable for a jet boat bottom but, in my view it a nobel experiment worth a try.

L
Re: Power Drifter Project
January 10, 2012 06:23PM
That is an interesting boat. I want one myself.

I've often wondered about a hybrid jet sled, where the bottom was aluminum and the first 6" of the sides (welded to) aluminum, with the side panels above that and everything else some combination of plywood and/or honeycomb core.
An aluminum bottom panel with 1" honeycomb core laminated to the inside of the bottom would go a long way toward deadening the annoyingly loud sound a tin boat usually makes as it scrapes over shallow drops.

Jet sleds have to be able to take enormous impacts. I ran one with a buddy on the lower Big Horn in Montana once. Two days in a row actually. We started out a few miles below St. Xavier and motored all the way up to the 14 mile take out. And then drifted down, anchoring up at all the promising riffle drops, and wacked'em big time. And we had the river to ourselves too.

At the Big Horn access there were a good fifty trailers parked. We only hit bottom maybe twice, zooming upstream. You do your best to read the water and to slow down when you might hit. But we did hit a few times so hard it sounded like a bomb going off underneath. That was a 16' Jon boat with a 60hp outboard and jet pump.
Re: Power Drifter Project
January 11, 2012 12:56AM
Thanks for the responses,

Yes I would guess its somewhere around the 60/40 range, though I'm not quite sure since I just found the photo online.

Sandy, thats a good idea to incorporate an aluminum bottom with a ply, or substitute, sides. The best of both worlds!

Now only if boat building was cheaper :)
Re: Power Drifter Project
January 11, 2012 02:49AM
I would love to build a jet boat some day.

Sandy, the idea of a sheet of aluminum bonded to the outside of some core material should make for a strong bottom.

Does epoxy bond to aluminum? Would it be possible to make a chine joint with plywood sides and a metal bottom?

This is a new topic an and interesting one.

At the old shop we had a piece of 1/2 inch thick aluminum honeycomb. One side was thicker then the other. I was used as a base for thing granite counter tops. I tried to smash it with a rock. I just dented. Not sure how we could work with it but it was an interesting material, very strong and I bet it's not a bargain.
Re: Power Drifter Project
January 11, 2012 05:54AM
Aluminum honeycomb core would make a great bottom, but it costs like a Saudi Arabian call girl.
I'd look up the price now, but my network connection is suddenly so slow I can barely use it.

You can bond epoxy to aluminum. I called the West System help guy once, many moons ago.
I can't remember his exact instructions. Had something to do with light sanding and washing with a mild acid solution,
prior to layup.

I doubt you could bond plywood or honeycomb core sides directly to a thin sheet aluminum bottom panel.
Maybe. But I can't see how.

What you might be able to do (if you had a tig welder) would be to weld the bottom panel to a six inches high aluminum side panel. That six inch vertical chine could be glued and maybe riveted to honeycomb a core or plywood side panel, in order span the rest of the distance up to the desired gunwale height.



Re: Power Drifter Project
January 11, 2012 09:32AM
One option would be to maybe bond insulation foam sheets to the aluminum then you could bond your plascore or plywood on top of that which may make quieter, more solid floor.
Re: Power Drifter Project
January 11, 2012 05:53PM
I have been getting ready to build a jet sled, I am planning on using a plywood that is covered on both sides with lots of fabrics , then put in 3" tall stringers every 16" on the inside. Then I will pour flotation foam in and then top that with another sheet of plywood that is fiberglassed on both sides. This will end up being a 4" thick bottom, the boat will be like 70" wide at the chine and 18 feet long. I have been looking for a motor in the 100 hp range, you can find them for around 2000$ if you don't mind it being from the 80's .
Re: Power Drifter Project
January 11, 2012 06:11PM
I would not use expanding foam. Water seems to find a way into places like that. My recommendation would be removable glassed foam blocks which can be held in place many ways. That way if you do put a rock through the floor at 25 MPH the repair will be simpler.

Just my opinion, I am often wrong and many would say I am always wrong.

L
Re: Power Drifter Project
January 11, 2012 09:57PM
lhedrick Wrote:
-------------------------------------------------------
> many would say I am always wrong.

You mean it's not just me?
Re: Power Drifter Project
January 14, 2012 02:28AM
Hey guys, this looks like the exact project I've been hunting down for some time. My big sled is just too much for one person to handle and I work an alternative work schedule (shift) now so I really need something light for one person. I have an aluminum boat so I can say with out hesitation that it's not what you want on the bottom of your boat. I would and am thinking more along the lines of UHMW or a similar high molecular wt plastic. I know it's heavy but it slides where aluminum grips. I would think a couple layers of kevlar and glass with the uhmw would be the real trick. I know this is my first post so for what it's worth, been down the aluminum road before, that's why I'm looking to build.
Re: Power Drifter Project
January 14, 2012 03:07AM
I appreciate your post.

I have an aluminum V-bottom now. And I love it. Fun boat. I've never owned an aluminum drift boat.
I've heard people complain about aluminum "gripping" the shallow riffles. But never experienced it.

I did build two fish shocking boats for the Montana Fish and Game a while back. Mid-1980s actually. Jesus. That was 30 years ago. They asked me to build two boats: a wide, 16' square-ended boat for work on Montana's Big Hole river, and a female-molded, Kevlar Buffalo Boat for working a small local river called the East Gallatin.

The one thing they said was: "No aluminum on the bottom. We tried that." Those boats both carried huge mid-boat water tanks for collecting sample fish, and for keeping them alive long enough to count tag and release. Each boat had a gas generator, a long fat rubber-covered cable and and a shocking probe. Plus a big long-handled net and weighing scale. Plus passengers. 2 passengers for the East Gallatin Buffalo Boat and 3 passengers for the Big Hole boat. That's a lot of weight.

Anyway I asked them--"if it can't be aluminum, don't you still need a big metal surface on the outside bottom, for the return current?"

They said: "Yes. Exactly. But you can use steel or stainless steel. USE ANYTHING BUT ALUMINUM]!" I could tell they knew what they wanted. Both guys wagged their heads and shook both palms-down hands sideways when they said: "no aluminum."

This was because--with all that weight--when they got stuck they really got stuck. And anything (anything) was better than aluminum. That's what they said.



Re: Power Drifter Project
January 14, 2012 03:14AM
If you could rivet UMWH (or what ever it's called) to the bottom of a stiff stout boat (regardless what the boat is made of) then you'd have something. UMWH was good on framed wooden boats. Or so it seemed. But UMWH gets screwed in place on wooden boats. And the required screw holes cause the wooden bottom to rot out in 4-5 years. But if you riveted that stuff to aluminum that wouldn't happen. You'd have a sledge-hammer bottom that slides over the riffles...with a replaceable skid shoe.. where nothing rots.

....just a thought. I never built it.

Actually there is one other problem with UMWH. At least when you tried to put it on a wooden boat. It expands and contracts faster than wood. So after certain sunshine water temperature conditions you'd get huge bulges of plastic underneath the plywood, between the screws that hold the sheet on. And those bulges would fill up with gravel, quickly. So then you got stuck with the gravel for ever. No matter what. It might be different with aluminum. Somebody would have to try it and see.



Re: Power Drifter Project
January 14, 2012 03:25AM
Now I hadn't really thought about SS but it glues pretty good and I'll bet if a guy were to rough it up with some 40 grit or 25 grit you could glue a sheet to the bottom. There is also a new spray on material that's supposed to be almost as good as uhmw sheet (not really sure how that could be...) It sprays on like the bed liner stuff and adhears like no tomorrow. Some of the jetboat MFGs are offering it, mainly up north in Canada where everything is skinny. The prices I've seen are around 3k if it's done during production as they have to flip it bottom up to apply. I'll try to find the name. But back the original question, uhmw on the bottom does a great job of dispursing the load from a rock blow on the bottom so with glass and Kevlar it would be pretty darn tough. It's a bit heavy but it's really good at its intended purpose.
Re: Power Drifter Project
January 14, 2012 04:06AM
It does expand and contract a bit and yes it does have to be bolted on and I would think some sleeves would be need to be run through the bottom or maybe use blind nuts in the floor and then glass. Either way probably more work than a few repairs in in the bottom glass. It seems to work pretty good on aluminum.
Re: Power Drifter Project
January 16, 2012 02:51AM
So for power comparison. My buddies little green boat that we take into god knows where is a 15 foot G3 welded skiff, weighs in about 400 by itself. It's powered by a Merc 25 jet. The power head is a tweaked 30. It'll run a couple fat old guys at about 20 mph and it conservatively runs in 2" of water when on step. When talking jetboats and running skinny, the throttle is your friend, never slow down.
Re: Power Drifter Project
January 20, 2012 10:41PM
My next project will be a Jet boat for sure.

As for the aluminum bonded plywood, I have been working with this product for my skiff bottom. It is furniture grade exterior plywood with an aluminum skin on one or both sides. It cuts with a regular power saw and has no voids from what I have found yet.

It is used for making traffic signs in the great white north.

http://www.sterlingpromotions.ca/Omega-SignPly%AE.html

Info:

SignPly Single-sided, painted aluminum over furniture grade exterior plywood core
Benefits
Impact resistant, colorfast surface is warranted not to fade, flake or peel.
Average outdoor life expectancy is 5 to 7 years if properly edge sealed.
Construction
SignPly is composed of painted aluminum face on premium furniture-grade, exterior plywood.
Factory-baked polyester paint on the finished side with a mill-finished aluminum backer to provide balance and prevent warping.


For Plans, I keep coming back to this, the Rogue Runner https://www.boatdesigns.com/Rogue-Runner/products/756/

Andrew
Re: Power Drifter Project
January 20, 2012 11:33PM
I would like to know more about your project. A new dedicated thread would be good.

What will you be using for a power plant. There seem to be lots of jet drives but they are for the big motors, 300HP and up. I have not found a small unit for a 50HP motor. I wonder if there would be a way to get a jet pump from the wave runner builders? The inefficiency of the outboards seem obvious when water needs to be deflected upward into a pump where the axis which is 90 degrees from the river flow. Inline jet pumps would be the way to go if we could find them.

I would also like to know more about joinery using the aluminum covered plywood you found. I know you could make your own also. Back in my college days I had a summer job at a laminated plant. Wd bonded steel and aluminum to plywood, then framed the pannel and they were used on big rig trailer for the doors. We used contact cement to do the bonding. Once and a while a mistake was made and a sheet contacted the plywood out of position. The contact cement bonded and it was a major production to salvage the plywood sheet using a lot of solvent.
Re: Power Drifter Project
January 21, 2012 12:02AM
Re: Power Drifter Project
January 21, 2012 01:46AM
I have seen videos of this one running. Build from a salvaged waver runner setup. Very nice job.
Re: Power Drifter Project
January 21, 2012 02:33AM
There are jet units for smaller motors. I have seen a few Rouge 16' power drifters floating around my neck of the woods. They were running 30hp Honda 4 stroke outboards with jet drives and tiller steering. They are not that fast but much lighter to row around than the bigger gun dedicated sleds.

I also see a lot of 75 to 90 hp rigs on the "smaller" 16-18ft dedicated sleds.

With the 30 hp jet rig you are restricted to lighter boats and only two occupants. But they do work.
Re: Power Drifter Project
January 21, 2012 11:50AM
The Yellowstone is the longest un-damed (undamned?) river in the lower 48. Not surprisingly there is a large and active community of jet sledders in Billings Montana. There's even a club down there that tried to get me to give up the "Montana Riverboats" trade name about ten years ago. It just occurred to me the Billings Craig's List might be a good place to shop around for used motors and sled hulls.
Re: Power Drifter Project
January 21, 2012 04:25PM
I have done a lot of reading on jet outboards. 15 - 20 percent power loss.

From what I have learned all the jet pumps put on outboard come from one company "outboard jets" in California. Take a close look at the pumps on all the jet outboards. They all look the same.

The main problem is that the pump is above water level. To get the water up into the pump when the boat is on plane, part of the lower unit drags in the water deflecting the water upward killing efficiency. Like putting a 2X4 block on the bottom of the boat. An inline jet pump doesn't have this problem.
Re: Power Drifter Project
January 21, 2012 04:35PM
Now this is a jet boat

http://www.youtube.com/watch?v=iHlWdS3qnjA

When money is no object and you have the United States Federal Reserve Bank to print the money you can have anything.

Pearce Ferry rapid is once again covered by Lake Mead. Good riddance, I hated that rapid.
Re: Power Drifter Project
January 21, 2012 05:17PM
My power drifter is little more than a twinkle in my eye at this point.

I am working on a framed double transom dory right now that is about 30% done so I have to get that out of the way.

My plans are to use the aluminum faced ply for the bottom by doing a overlapping butt joint where the aluminum overlaps the face of the aluminum on the next piece. I plan to join them with something like System 3 T-88 and them tape and glass the seams on the inside. I am pretty happy with the bond of the aluminum to the wood. To make the overlaps I had to separate the wood from the aluminum after my dado cut was made to create the overlap. This was a major PITA. Furthermore, I put some cutoffs in a bucket of water and sealed it up for 8 months. I still could barely separate the plys with a chisel.

As for the motor, here on the Bow, a 40/30 outboard jet is enough to get you up river with enough jam. Being a bigger guy I want to go with a console steering system rather than a tiller steer to keep less weight out of the back of the boat f I go out my self.

Here is a jon with 3 buddies going up the 'mo without any problems. I have been in this boat and it cruises nicely.

Andrew



Re: Power Drifter Project
January 21, 2012 05:37PM
Re: Power Drifter Project
January 21, 2012 05:53PM
It doesn't really take the fed to put a big boat on the water. That's pretty plain jane compared to many....
Try some of the vids on here. There's a video section and in the forum there's another. It's a good place to get info if you're looking for powered things. Take everything with a grain of salt, it must aluminum, V8 or diesel.....

The Mean Chicken!

As far as finding used jet OB's, Seattle, Portland, Boise. Lots more people with boats.
Re: Power Drifter Project
January 21, 2012 06:56PM
I wouldn't call twin 500 HP diesel hamilton Jets plain Jane.

150,000 perhaps, 3/4 the value of my home, perhaps 50 gallons per hour burn rate at 4 dollars per gallon

I doubt I even know one person who could pay for such a thing.

If that kind of rig is plain Jane then I need to find a way to upgrade my life.
Re: Power Drifter Project
January 21, 2012 08:28PM
I'm guessing you haven't priced many big jet boats. Go to the mean chicken and look a some of the boats there. A number of twin diesels and I believe the average price point for those is more along the lines of 250k. Yes that boat no matter what the power it has, is plain jane, it's a work boat with no amenities. Sorry if you think it's fancy, it's just not.
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