How thick to build a boat?

Date 11-26-2012 14:24

Ladies and Gentlemen,
   Around boats all my live. Suggest you get a set of plans from a reputable concern. Alternatively look at a manufactured boat to about what want to build and copy it. Put in buoyancy is strongly suggested. There was an article in "Popular Mechanics" plus fifty years ago of a home built boat built of two car hoods of the day welded together. A subsequent issue mentioned the boat sank killing the one that built it. It sticks in my mind that why I am posting. Hope I did you some good. I look forward to hearing from you.
Sincerely
Len Andersen weld@spemail.org
   914-536-7101   / 212-839-6599    8-4 New York Time , 4042 FAX , Co-worker 6381 / 914-237-7689 (H)
POB 1529 / NYC 10116-1529 ( $1100 per year Caller Box GPO NYC / Most Secure Service At Largest Post Office )
   www.lenandersen.com

By Billyboy (*)

Date 11-26-2012 14:35

I have built a few boats, but never for that purpose. I personally think you are off on a couple things. First, I would use all .125 5086 aluminum. Second, I would use all longitudinal runners from the transom to the end of the rack. This allows your boat to absorb impacts without putting hooks in the bottom that cause drag. Call Paul Willging at Phowler boats for some tips. He is a first class guy and is always eager to help people out. What are you planning for a transom?

Just my $.02

By Stringer (***)

Date 11-26-2012 23:39

With a 75 horse on a .125 hull you should be able to bang it off icebergs all day.

By Chris2626 (***)

Date 11-27-2012 00:34 Edited 11-27-2012 02:58

I don't see why I can't use .080 on the sides and .100 on bottom. The Phowler boats would be way to heavy for what I want and honestly I have given up calling guys like these because they don't want to help a home builder unless they get money out of it. Yall are right I wouldn't be building it completely from scratch I would get some ideas off other boats before i started.

5086 is it a much stiffer aluminum then say 5052 because I have read that the 5052 is real flexible. With 5086 does it form really well can i have chimes or crimps bent into it?

Billyboy I have thought the same maybe I should try and use braces the full length of the boat but really only need them for about 4-4 1/2 foot because way less then that is all that is gonna be running in the water so I don't really see why I need them so much for the full length. I have seen this done on another flat bottom boat and this boat is fast running in the low 80's. I have seen a V hull with a pad and it had the brace the full length of the boat and I agree this is a good method. It's really pretty stupid all the dam jon boat manufactures running those braces width wise the full length of the boat.

I have seen a transom that would be a real b*tch to build but it looks like a ranger bass boat transom instead of it being normally straight across it is stepped back like a build in jack plate to get that motor further back, so kinda debating on this. I have seen other transom basically having a piece of channel 4 inches wide ruffly going across the top of the transom and two 3 inch channel pieces going down and tying into the bottom plate. I have seen this done on a lot of boat down here in Louisiana.

Thanks
Chris

By welderbrent (*****)

Date 11-27-2012 02:03 Edited 11-27-2012 14:13

The first time I thought it was a typo, but twice... YOU MUST BE KIDDING OR DON'T REALIZE WHAT YOU HAVE TYPED!!??

You want to use material OVER 3/4" thick on the sides and less than 1/8" thick on the bottom. Think about that. Now, the thin material on the bottom actually is on the heavy side but would work. BUT, 3/4" material on the sides?? Talk about overkill.

Better do some more research before you get too far along here.

Have a Great Day, Brent

By Chris2626 (***)

Date 11-27-2012 02:54

dammit .080 lol My whole day today was screwed up lol may need to go drink a few and kill off those bad brain cells

By DaveBoyer (*****)

Date 11-27-2012 03:22

The "V"s You want in the bottom take the place of longitudinal stringers in a conventional boat.

There are (2) factors that You need real numbers for, and I don't have them.
1) Softer material [5052] can be bent to a tighter radius without fracturing when forming those "V"s than harder material [5083].
2) Thinner material can be bent to a tighter radius without fracturing than thicker material.

If You form straight "V"s in a piece that is straight end to end, You will have a real hard time pulling any curvature into it. The harder & stronger the material the greater the problem will be.

You really need to BS Your way into a plant building these boats [let them think You will buy one], and see just how they do it.

Usual one off & amateur built boats are often simple curve, and if compound curve, rolled on a sort of English Wheel.

By Chris2626 (***)

Date 11-27-2012 03:46

That makes a lot of sense Dave because the mud boat builders here in the south seem like a lot are building with 1/8-3/16 5086 and there all flat and no V's / Chimes are bent into there hulls. Although they need the boats to slide really well to. So maybe the boat will have to be build 5052 aluminum. I guess the best thing to do now is to call one of these company's up that sell the aluminum and can form the aluminum into these V's and ask them.

The good thing is I do want a long slow gradual curve for the bottom so if putting V's in restricts me from doing a hard bend well that would be fine by me.

Guess i need to start hitting up some boat places around and see how they make there boats.

Thanks Dave

By Billyboy (*)

Date 11-27-2012 19:55

Be careful not running your ribs the whole length of the hull. It isn't about what hits the water, its the strength of the entire hull. 5086 is the most widely used aluminum for marine use and it bends really nice. I am confused with the "Vs". are you thinking like a factory jon boat with the rippled bottom? You don't need those. They act as the ribs. You are using ribs inside the boat. If you want them for sliding reasons, just weld three pieces of angle to the bottom and don't pay for the time on a break. Check out this guys build:

http://www.mudmotortalk.com/mmt_v2/viewtopic.php?f=4&t=34455

I know you don't want a mud boat, but the basic consepts still apply.

By Chris2626 (***)

Date 11-28-2012 00:00

The V's which are the Chimes bent into the bottom plate... yes.. like the factory Jon boats are. I have ridden in a boat that had four pieces of angle aluminum welding to the bottom now maybe they didn't hang down deep enough in the water while the boat was running but this boat would slide so dam bad in a turn it really freaked me out riding in it.
My hand me down 12 foot aluminum boat really wasn't to bad it didn't slide much in a turn and it had I think three or maybe four chimes bent into the bottom plate the full length of the boat. I'll feel better if the chimes/V's can be bent in the bottom plate when I go to build it and I will make sure there is bracing the full length of the boat.

Can you tell me is 5052 cheaper to buy then 5086?

Thanks for the link my thought was that you could manually work it a little at a time and curve the bottom plate gradually upwards towards the bow but I guess a brake is really needed for this curve. Guy down the road from me I found on another boat building forum I don't think he used a break but i could be wrong on that.

Thanks for the link.

Chris

By Billyboy (*)

Date 11-28-2012 12:06

A break is not needed to bring the rake up, unless you try to do the crimped vs in the bottom. It is your boat, but the more research you do, the less desirable those crimps will become. The chimes on the outside corners of the floor determine how the boat will turn more than anything else on a flat bottom. There are square, tapered and round chines. The cost difference of 5052 compared to 5086 isn't very much, but availability might be an issue. If you are in LA, check out "uncle j's boats". He builds custom boats and sells kits for what ever boat you design. He has built some serious skiffs with 250hp outboards. Whatever you do, post up some pictures so we can watch your progress! :grin:

By Chris2626 (***)

Date 11-28-2012 13:08

Thanks and thanks for the link to the mud boats, I've actually typed in on google search and have find a few other people building mud boats and have gotten ideas on how they did it. I looked up uncle J's boats and he is maybe a couple of hours from me and hell if he will sell a so called Kit or plans then maybe i'll call him up and see what he says. I've learned for a few things i've built if you study pictures and read all you can you can build whatever you want. i'll be studying the sh*t out of this till i'm blue in the face and go from there. I'll be sure to post pictures when i do this.

Transom angle I'm curious of, my boat now the transom is about 19 degrees what would you recommend for a transom angle? I have heard a guy tell me he wouldn't go anymore then 15 degree and well doing this you wouldn't be able to trim the motor down as much. I don't know what that would be like although this guy doesn't run power trim on his motor either.