Aluminum de25

[Rziel]

Has anyone built a de25 from aluminum. I think I found one on YouTube. Search downeast 25 aluminum. I want to build a down east style boat from aluminum but can’t seem to find any plans. All the aluminum boats this size are more of a heavy high powered fishing boat. The de25 looks like a great design fore cruising. Does any anyone have any thoughts on building this plan from aluminum?

[jacquesmm]

Down East is just a boat type name. You can build my DE25 from aluminum and she will float and perform correctly but you are on your own for the scantlings. In weight, aluminum is very close to plywood-epoxy but you must redesign the framing and choose the plate thickness.
All dimensions can stya the same and you can use the developed panels shapes.

[TomW1]

Jacques is the designer so take his words to heart. With the price of aluminum what it is today you may want to reconsider building a boat in aluminum. I worked for a major aluminum company for many years, so make sure you get the right alloy for your use. I don't remember it off the top of my head, I think it is 5083, but it is specifically for marine use. 5052 grade used to be the standard but 5083 has better corrosion resistance, workability and weldability. I cheated once it popped into my mind as I typed, I went to my source.

Well good luck and much success. Please post pictures of your build. I would love to see a complete aluminum boat build on here from start to launch.

Tom

[Rziel]

I know aluminum will be heavier than the ply epoxy but I live I southeast Alaska and plan to be on and off the beach often. Mostly rocky beaches and lots of rain you can watch wood rot right in front of you. Looking for a tough rugged boat that can handle some heavy use.

[TomW1]

Go for it. I know Tracker builds there 20' V-hull bass hulls out of 1/4" 5052, they will take a lot more punishment than your DE25. Tracker uses smaller 3/16 on there smaller boats so I would say go to 5/16 for the DE25 for the hull. Strength of aluminum is not strait line it is exponential. You don't want to go to big or you won't be able to bend it to the frames. You may also want to put a couple of extra frames to help you form and tack the pieces in place in the forward portion. The other thing you can do to reduce weight is in the frames cut out holes so that you have 3" of aluminum on the top and bottom and 8" between holes in each frame. This will give you a good weight reduction in the frames.

Well good luck, I think you will have a great boat.

Tom

[Fuzz]

Welcome, we need more Alaskan builders I do not know how to weld but understand the desire to build out of aluminium. It works good for scraping on and off beaches and normal harbour rash. I think the DE25 is about the best design here for use in this part of the world. If you do build one please start a build thread so we can follow along.

[OneWayTraffic]

Most NZ boats of that size have either 5mm or 6mm hull bottoms and 4mm on the sides. Surtees use 6 stringers, I'm not sure about the others. Gerr recommends 5mm hull with at least 25mm high longitudinals on 250mm centres. I know that there's a lot of other details on Aluminium building in Gerr's book, but I have the highlights in a spreadsheet. Most boats in that size are designed for motors and speeds much more than the DE25. I would think that if you use 6mm plate the boat would be very heavy.

[fallguy1000]

That boat doesn't need a 6mm bottom. I am no expert, though. It just seems too heavy; especially since you need some framing and still the long t's, which are likely boxes?

The thing that drives bottoms thicker is horsepower, aka speed.

If you are gonna power that thing with something going real fast, different story. What you need to be careful of here is making it super heavy and requiring more power.

If you plan to fly off waves, etc., slam into breaking seas, plan is different.

Making a 20' box beam from 5mm versus 6mm aluminum with a 12" height is a 6/5 percent weight gain. Which is rather lots I get 30# delta per stringer roughly.

Boats are very weight sensistive and adding 30# by making a stringer too think is tough. The issue for aluminum is can you work thin(ner) material without deformation..

The difference in the bottom from 6mm to 5mm, for example, is 100#, roughly, perhaps a bit less.

[OneWayTraffic]

If it were me I would follow Gerr, I can look up the full scantlings if you like. Otherwise employ a naval architect that designs in Aluminium. The Gerr scantlings will be safe and sturdy. Agreed with Fallguy that 6mm is overkill for a boat designed to go at reasonable speeds.

[fallguy1000]

If it were me I would follow Gerr, I can look up the full scantlings if you like. Otherwise employ a naval architect that designs in Aluminium. The Gerr scantlings will be safe and sturdy. Agreed with Fallguy that 6mm is overkill for a boat designed to go at reasonable speeds.

Gerr would be heavy; fyi.