aluminum Flat boat question

yes aluminum is louder but after owning a carolina skiff and seeing how badly that boat was designed i don't think I will ever go back to fiberglass. There to heavy.

 

I have a aluminum flat boat and it is rated for a maximum of 3 HP this sounds like an awfully small motor is it safe to put a larger motor on like a 5 or 6 HP?
Thanks.

 

you can do whatever you want really, I know of guys who have taken a 75 hp omc soup it up to about 130hp and put them on a 12ft boats

 

I just tested out a 15' x 50" bottom flat that I built. No plans, just and idea and it has turned out great. The material is 1/8" 5086 H116 all the way. I am running a 40 merc with CMC PT130 power trim. I am still tuning and jacking the motor up to get the best performance. Along with testing trim tabs also. I have run 37.5 mph with 2 people and ice chest. The bottom chins/ribs are 2" sch 40 half pipe. Boat handles like a dream. I have more work to do, but testing has been very good.

A good plasma cutter, metal saw and spoolgun wire feed are a must. I did get a metal blade for my table saw. The better the cut, the better the fit, the better the fit, the better the weld.

I did a but weld on all my hull and that was a mistake. The next one will have the sides inset on the bottom just a little as to make it a "T" joint all the way. The biggest advice that I can give is that preperation makes a big difference in time and finished product. I have built my first and learned so many trick and things to do different on the next one.

 

Do you have any pictures of it?? I'm really leaning towards a miller syncrowave 250dx I really can't stand mig. I do a lot of mig at work.

 

I have run a Syncrowave for a while and they are great machines, but way to slow for boat building. I am looking to get the Millermatic 350P Alumapro. Quality welds and less heat distortion. Here is a link to the boat. I am not finished with her yet. Just a test run and then back for more work. I have to finish the rod boxes and the clean up for paint. This was my first boat to build. I have learned so much and the next one will go much better and faster.

http://imageshack.us/photo/my-images/801/boatbr.jpg/

 

Do you have the braces hidden on the inside? What part of Louisiana are you from? Very nice looking boat.

That 350P would be a nice machine I know where i work now they were talking about maybe buying one. I like tig a lot more just more control but you're right it can distort more if you're not careful.

 

Thanks

There are no braces in the bottom. I have 2 runs of 2" sch 40 half pipe on the bottom from bow to transom and one run of 2" half pipe from bow to about 5 feet short of the transom in the middle. The back seat is welded solid to the floor and the front split seat uses 1 1/2" x 1/4" flat bar all the way across with seat welded over that. All material is 5086 1/8". I live outside of Bogalusa.

This was my first boat build. I have the rest of the material to finish it out now. The piano hinges for the rod boxes and latches. I have 2 more of the deck hatches also. One for the back seat with a liner for dry storage of your phone and wallet in a rain storm. The last one goes in the bow seat for storage. All the wiring will be in the angle on the right side wall and the bait well piping is in the other angle. All hiden and welded 1/2" aluminum pipe. I have built this boat for fishing on the Pearl River. Running trot lines and nets. I am still playing with the power trim and getting motor jacked up to run the best. I am running 37.5 mph now. Cavitation plate still under water when running.

 

You're just up the road from me, I'm in Covington. I was actually just at Richards landing racing my boat Saturday with the bogalusa boat club. You should try racing out there and that Merc you got will freaking fly when set up right. You need to have it so that cavitation plate is level or even above the bottom of the boat. Mine is currently 2 inches above the bottom of the boat and I'm looking into welding a pad on the bottom of it for more speed.
Seriously you want that cavitation plate to be at or above the bottom of the boat. You're boat with 6 carbs is capable of running over 50 mph.

The forum boatracingfacts.com is where a lot of those bogalusa boys post.
Do you have anymore detailed photo's of your boat build? One of these days I'll build one, I just got to much going on now but I have learned a lot since I started this thread.

Where did you buy your aluminum from?

 

If you PM me with an email, I will send some pics of the construction. It took me about 4 days of work and not very steady work to build it. I got the material from Sunshine Metals in Harvey. Great to deal with.

I had to go back to work, so I did not get to finish setting the motor up like I wanted. I have the power trim bolted at the bottom and clamped at the top. The bottom holes are slotted with 2" of adjustment. I wanted it right before I drill the tops. I have raised it 1" more, but have not run it yet. I can go 1" more before I need to move my bottom holes. No big deal with a TIG welder handy. I actually used my old fiberglass boat for a pattern. But that was all. This boat don't slide and don't sit as low in the water. I could only run about 28 mph in my old boat on the river and be able to make the turns. I can run wide open now with no problem.

The first run I did in the boat. I figured real fast that I needed trim tabs. I could not keep it in the water. I have some more playing to do. I am gonna put the pontoon boxes on the back and see how they work. If I don't like them, I will just take them off. I am gearing up to finish this one and then start another for my 30 Yamaha. I have a new design idea that I think will work very well.

 

The hull pieces cut and ready for prep.
http://img135.imageshack.us/img135/3862/img1315g.jpg

Tacking them up.
http://img822.imageshack.us/img822/3882/img1317cg.jpg

Taking shape and back seat tacked in.
http://img28.imageshack.us/img28/8705/img1320vt.jpg

Another view.
http://img513.imageshack.us/img513/1473/img1323kv.jpg

The front seat going in.
http://img152.imageshack.us/img152/189/img1324jb.jpg

Girlfriends 9 year old daughter wanting to help and learn to weld. She did a pretty good job.
http://img507.imageshack.us/img507/6411/img1359w.jpg

The middle seats going in.
http://img525.imageshack.us/img525/6765/img1342w.jpg

Transom bracing. (Overkill, but this boat will hit stumps and logs from time to time)
http://img7.imageshack.us/img7/249/img1361lx.jpg

A look at the bottom and the half pipe.
http://img845.imageshack.us/img845/6291/img1354i.jpg

My help. Girlfriend wanting to help weld. LOL
http://img14.imageshack.us/img14/3267/img1353o.jpg

I don't have any yet with the power trim unit installed. I did this using a Millermatic 211 with spoolgun, Hypertherm 30 plasma cutter, metal saw and table saw. It will be about 3 weeks before I can get to work and finish it.

 

email address is chrissport21@hotmail.com for some reason it won't let me send you a PM

 

Just had a chance to look through the pictures and man that thing is nice. I guess the pipe on the bottom is enough for strength. How thick is the sides and bottom?

 

I forgot to say when i worked at Textron in New Orleans east welding aluminum boats for the coast guard I had seen guys weld the outside of the boat like a T joint you know and take a air gouger and trim it down so there wasn't such a lip sticking out. This was a very clean look when finished and probably much easier then a butt weld. I didn't weld to much on the outside of these boats I was always on the inside but dreamed many times of building my own boat hahaha

 

Thanks, it was a very good learning curve for me. The bottom and sides are all 1/8" 5086 H116. I wanted a clean floor. I have seen this done before on homemade boats and works well. I did stretch the limit with the 50" bottom though. The next one will be a "T" weld on the side to bottom connection. One thing that I did learn with the 1/8" material is to use1/4" x 3" flat bar tacked on the floor to keep it nice and flat. I have a pretty good procedure for the next one that will make life much easier. This being my first, there was some rework. I have seen several cases where just a few minutes of more prep to keep small pieces straight when welding would have saved hours in the long run.

The back seat is solid across the floor. The middle seat is also solid, but the pics don't show that. I have 1 1/2" x 1/4" flat bar across the floor and piece of 1/8" diamond plate between the seats. That is the only step up in the boat. There is a 1/2" roll in the bottom from the transom and through the back seat, then it is all flat.