# 1980 Grumman 4.6 Sportsman all aluminum build



## Flatbotm (Aug 8, 2013)

Yesterday I bought a 1980 Grumman 4.6 sportsman. I regret selling my 1542 I built so I decided to build another boat. I picked up the boat, trailer, and 35hp Johnson for $650. I built my 1542 pretty heavy so I have new goals in mind for the Grumman. Light weight and all aluminum. I chose this Grumman for its size. It's a 1554 and 71 at the beam. I love my little 12' crestliner but I miss being able to walk around. Here are the pics of what I'm starting with. I started stripping the boat as soon as I got it home last night.


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## thudpucker (Aug 8, 2013)

I LIKE that Bow arrangement. I wonder if I could convert my little 14' Jon to that?  
Nice looking and functional too.

i never thought I'd like Yellow, but it looks good on your boat.:lol:


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## Flatbotm (Aug 8, 2013)

I probably won't keep the boat yellow. It doesn't look bad. I'm going to return the boat to a layout more like the original. The flooring that was put in by the previous owner was 1/2 plywood. It is already rotting and has a lot of flex. I'm tearing it all out and putting in the alluminum floor. 

This is how the sportsman originally came.


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## Flatbotm (Aug 8, 2013)

Does anyone have a suggestion of what thickness aluminum to use for flooring? 1/8th?


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## Ranchero50 (Aug 8, 2013)

[url=https://www.tinboats.net/forum/viewtopic.php?p=325309#p325309 said:


> Flatbotm » 23 minutes ago[/url]"]Does anyone have a suggestion of what thickness aluminum to use for flooring? 1/8th?



.062 or .080" if you plan on supporting it every foot or so. .100" get's heavy quickly. My front deck is .062 with a pair of 13" x 21" spaces with no support and I don't notice it flexing. What is supported is 1/8" x 1" angle or some 1" x 3" C channel extrusions with a couple risers. Most folks really underrate aluminum's strength and go way oversize.


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## Zum (Aug 8, 2013)

Most factory floors on aluminum boats,are no where near 1/8".
Like Ranchero50 mentioned,depending on your spacing,you can go smaller.

Nice find BTW,does the outboard run fine?


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## Flatbotm (Aug 9, 2013)

The 35 Johnson purrs like a kitten. Thanks for the info on the aluminum thickness.


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## Flatbotm (Aug 14, 2013)

Last night I got the floors all tore out.


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## thudpucker (Aug 14, 2013)

Now it looks pretty good, and a good place for a Shop Vac too. :LOL2: 

That Yellow is a good color for that boat too.
I envy you the energy to take on that much of a project. If we lived closer, I'd come over and watch you work! :mrgreen:


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## shaggs (Aug 14, 2013)

I'm using 3mm or 1/8th checker plate on my floor and casting decks but thats because I'm over 220lb
The aluminum is actually lighter than the timber I pulled out


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## Flatbotm (Aug 15, 2013)

I decided to go with 1/8th as well. I had a half sheet already and my dad fishes with me some and he is 265. I didn't want the floor flexing on him. I picked up the sheet yesterday.


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## Flatbotm (Aug 15, 2013)

I did the calculations and I should still be able to save 50ish pounds


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## Flatbotm (Aug 20, 2013)

Looks like I have more work cut out for me. While inspecting the stringers I found a dozen cracks. It's amazing that the outer skin didn't crack! I started prepping last night and got my spoolgun hooked up.


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## Flatbotm (Aug 21, 2013)

I ordered the rest of my materials today. 64 ft of 1" .125 6061 and 4 yards of nautolex storm grey vinyl.


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## magoo (Aug 22, 2013)

Those stringer cracks are worse than i thought. Good thing you tore her down.


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## hercdrvrwo (Aug 22, 2013)

Obvious aside -- what are some long term effects of not welding those cracks back up? Had a similar issue with mine -- I have 4 cracks on 2 different stringers from the bunks on the trailer. The boat hadn't leaked before and seemed structurally sound, so I bondo'd them and epoxied right over em! 

Thanks!
Herc


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## magoo (Aug 22, 2013)

Honestly what you did to fix your stringers was more of a "bandaid". Nothing wrong with that but it does depend how you treat your boat. I for one show no mercy and if there is something cracked it needs welded. Longterm will be it needs fixed for good. But ya ain't gonna sink. I bet my 1983 15' smokercraft was worse than his boat and she didnt leak or sink.
That poor boat took a beating.


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## Flatbotm (Aug 22, 2013)

Herc Magoo nailed it. It definitely would depend on how you use your boat? Bondo is for cosmetic repairs only. At a minimum I would rivet some aluminum stock across the cracks and spread out the load across the stringer. I suspect much of the damage to my boat was caused from power loading on the trailer. I wouldn't want to have to worry about the boat every time I cross a wake.


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## Flatbotm (Aug 26, 2013)

I just worked on getting all the cracks welded u this weekend. The spoolguns not pretty but gets the job done.



p


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## hercdrvrwo (Aug 26, 2013)

Thanks for the info -- I didn't mean to hijack your thread either man! So are you a welder or did you just go pick that up? Wondering if its something I can get for my very miner repairs so I don't have to keep taking my boat to the welder everytime I need something small done or working up some weird fabrication because I cannot afford the welder but need to keep moving ahead on the project.


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## Flatbotm (Aug 26, 2013)

I am not a professional welder but I've welded for about 20 years. I did have a job for some years that entailed some fabrication. I've had some tig lessons from the miller rep.. The welder and spoolgun set up I have for home is around $2000. I have a Hobart ironman 230 with a spoolgun for aluminum. Your going to invest at least $500 to $1000 to pick up a decent mig to weld aluminum. I would say anyone can do it it just takes practice. I started with a $299 110 Lincoln.


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## Flatbotm (Aug 26, 2013)

Here is my set-up. If you are going to buy a welder go with a quality name brand and it will last you the rest of your life.


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## hercdrvrwo (Aug 26, 2013)

So not something I can hop on and expect to do easily -- I know its a skill many practice at which is why I pay well for someone who knows what they are doing! When I have time -- or on my next boat because I plan to do all Aluminum vs wood like I am doing now.

Thanks for the info brother -- good luck on the boat and keep the pictures coming!

Cheers
Dan


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## Flatbotm (Aug 27, 2013)

It's not too difficult Dan. Aluminum welding with the mig spoolgun is fast. If you don't move fast enough you can make holes in your boat real quick. Tig welding gives you more control but is much more time consuming.


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## Flatbotm (Sep 9, 2013)

At this point I have all the cracks welded up, the vertical stringers riveted back in the boat, and added 1in square tube to them that I'm going to start building my front deck of. I also had to make some repairs where the previous owner had put lag bolts thru the bottom of the boat.


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## magoo (Sep 9, 2013)

Lookin' good brutha! You're gonna have a ton of room under that floor when it's all said and done!


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## Flatbotm (Sep 9, 2013)

Thanks my friend! Seems like I'm moving along at a snails pace but I keep moving. Tonight I got started laying out the front deck.


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## Flatbotm (Sep 13, 2013)

I completed a little more on the front deck last night. I riveted it to the sidewalls so I didn't melt the foam or catch it on fire.


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## Mojo (Sep 13, 2013)

Looking good man. Wish I had access to a nice spool gun set up like that. I've got to stick with the pop rivets.


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## kcatto (Sep 13, 2013)

Nice boat, and we are almost neighbors.... I notice eufalla in one of the pictures you posted of your boat...

I am just south of shawnee.... now a question please, as I am new to this part of the state I just moved here from west of yukon....

Where do you source your aluminum? I have a few places in the city and around el reno but both of them are about 80 miles away, I would like to get supplies closer....

I am getting ready to start my first boat build and I am trying to get stuff together....

thank you,
keven


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## Flatbotm (Sep 14, 2013)

Thanks Mojo. I worked for a place that spoiled me on tools. They had a millermatic 250 with a spoolgun plus a miller water cooled tig. I made it my goal for a few years to buy those tools for myself. Keven I'm in Ada. I couldn't find the square tube anywhere close so I bought it from onlinemetals.com which ships out of Dallas for us. It was close to the same price as it would have been for me to drive. The sheet I bought locally at sherells in Ada. If you find a better source let me know.


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## Flatbotm (Sep 24, 2013)

I haven't had much time to work on the boat in the last week. I worked on the framing for a few hours last night. I have some piano hinges ordered I should see them in the next few days.


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## stomper (Sep 24, 2013)

I like the way you are doing it with all aluminum. When I do my boat thats exactly what I am going to do. Light and will last for ever.


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## stomper (Sep 24, 2013)

[url=https://www.tinboats.net/forum/viewtopic.php?p=330261#p330261 said:


> stomper » 24 Sep 2013, 10:04[/url]"]I like the way you are doing it with all aluminum. When I do my boat thats exactly what I am going to do. Light and will last for ever. But again I am also set up for metal fabrication an have a millermatic 210 with a spool gun and all the other goodies to go along with it, tube bender, plasma, laithe, mag drill.......It all makes a project like this much easier. I like to help out others


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## Flatbotm (Sep 24, 2013)

Thanks Stomper. Ill be getting the tube bender out later in the project. It's one of those tools I don't use near enough to justify the $2000+ investment. But when I want to build something it sure is nice. I have about 140 ft. of 1" round tube for a custom top, grab handles, and a windshield. Back before I had a plasma I cut everything with a makita grinder. I've gone thru hundreds of cutting disks. Lol


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## stomper (Sep 24, 2013)

what kind of bender do you have. I built the gottrikes one and give it a lift kit with hydraulics. I can do a 100 degree bend in a single stroke with a 24" stroke cylinder. If you are interested check out the link below. Sorry didn't mean to hyjack your thread.
https://www.minibuggy.net/forum/shop-talk/17336-tube-bender-help.html
Is the tubing that you are going to use aluminum, if so what grade. I haven't tried to bend aluminum tube yet but I have read that it's not very idea. Some have good luck and others don't. I have thought about annealing it but then it turns soft and looses some of its rigidity.


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## stomper (Sep 24, 2013)

what kind of bender do you have. I built the gottrikes one and give it a lift kit with hydraulics. I can do a 100 degree bend in a single stroke with a 24" stroke cylinder. If you are interested check out the link below. Sorry didn't mean to hyjack your thread.
https://www.minibuggy.net/forum/shop-talk/17336-tube-bender-help.html
Is the tubing that you are going to use aluminum, if so what grade. I haven't tried to bend aluminum tube yet but I have read that it's not very idea. Some have good luck and others don't. I have thought about annealing it but then it turns soft and looses some of its rigidity. I have also heard that if you get a batch of tube that has just receintly been made, it will bend much nicer. I am interested because I want to build an ice shack out of 1" sq tube but don't want to waste the money buying a new die or time building one if it isn't going to bend.

sorry for the double post. I hit the Quote button instead of the Edit button.


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## Flatbotm (Sep 24, 2013)

I have a Jd2 model 32 full hydraulic. I've got 1", 1.5", and 1.75" 180degree dies. The dies are expensive. I think the aluminum I have is 5052. Ill look when I get home.


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## stomper (Sep 24, 2013)

That tube bends nice. the only tube I can find around here is 6061 which is not as forgiving.


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## Flatbotm (Sep 24, 2013)

Most the 6061 I see is T-6. Not bendable. I've seen some 6061T-0 that would bend nice. You can probably temper the t-6 to be bendable but I don't know much about tempering. I bought the 5052 from a aluminum recycling place that bought up surplus from Boeing. It was pretty cheap I wish I could get more. He even gave me 2 sticks for free that he ran over with the forklift.


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## Flatbotm (Sep 25, 2013)

My piano hinges came in tonight. (4) 12" (2) 16" (1) 23" (1) 55"


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## Flatbotm (Sep 26, 2013)

I am working on the Grumman tonight. I welded in a crossmember for the gas tank area bench. I had to weld it in front of the side boxes for the gas tank to fit.


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## Flatbotm (Sep 26, 2013)

The rear bench face was from some of my scrap. Riveted, welded, and some sealant in there too so hopefully no noise.


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## Flatbotm (Sep 27, 2013)

Here is a ghetto paint drawing of my basic layout. Nothing is exactly to scale. May add a few more access points and possibly a rod locker. Open to suggestions.


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## Flatbotm (Sep 29, 2013)

Ranchero50 you were right on with the aluminum thickness. 1/8th is definitely overkill. I'm going to try and use some thinner material in some areas. I underestimated the stiffness of aluminum.


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## Ranchero50 (Sep 30, 2013)

That's fine, as payment for good advice you can send me your bender when you are done. :wink:


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## Flatbotm (Sep 30, 2013)

Ranchero50 my bender would have come in handy when you extended out the transom of your boat! I we were closer I can always be talked into bending tube for cold beer! I wish I had a mill. I recently had to have some machine work done to put 2008 Ninja front forks on my 82 KZ1100.


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## Flatbotm (Oct 1, 2013)

I started making my first hatch and I made it too tight not leaving enough room for the piano hinge. I'll chop it down tomorrow.


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## Ranchero50 (Oct 1, 2013)

Try to account for your carpet as well. My goal was 3/8 at the hinge and 1/4 on the other sides. I had to put some fuzzy velcro down to keep it from vibrating as I don't have the carpet in yet.


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## Flatbotm (Oct 1, 2013)

I'm not running carpet. I'm going with nautolex and I don't think I'm wrapping it. I was going to cut it with a razor blade at the edge. I left 1/4 total both directions I think I was a little fat on my cuts. How much room do you need at the opposite edge of the hinge with no carpet? 1/8th? I was going to run a strip of scrap nautolex for the anti rattle?


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## Flatbotm (Oct 3, 2013)

Last night I re cut the hatch frame. Next time measure 3 times cut once. I started sanding on the yellow last night. What a PITA changing the color of this boat is gonna be. This yellow is some stubborn stuff.


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## typed by ben (Oct 3, 2013)

[url=https://www.tinboats.net/forum/viewtopic.php?p=331138#p331138 said:


> Flatbotm » 45 minutes ago[/url]"]I started sanding on the yellow last night. What a PITA changing the color of this boat is gonna be. This yellow is some stubborn stuff.


yellow is very tough. at work my boss accidentally had some machine guarding powder coated yellow and ended up having to remake it all because the yellow was so difficult to get off. even if you think you got it all off, when you sandblast the powder you just shove some of it down further into the metal. then when you bake it comes right back out and ruins whatever color you put over it. very aggravating.


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## Flatbotm (Oct 21, 2013)

My build is some what un-conventional I have a lot of scrap and I'm using thicker flooring than necessary so to finish out my floor framing I welded some kickers out of scrap.


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## Flatbotm (Nov 6, 2013)

I made a little progress on the Grumman in the last few days. Sunday I plasma cut all the sheet. My goal is to have it fish-able by the weekend. Just on my little water shed.


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## Flatbotm (Nov 6, 2013)

Here is another one of all the cut pieces sitting in the bow.


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## smackdaddy53 (Nov 6, 2013)

I missed this build, glad I checked it out! Nice project man!


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## Mojo (Nov 6, 2013)

Dude, 

You know you love the Yellow! You just have to embrace it.  

In all seriousness thou It's starting to look good. Great work!

Mojo


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## Flatbotm (Nov 6, 2013)

Thanks Smackdaddy 53 it is starting to come together. I won't have the rod locker done by this weekend but I'll have enough floor to fish out of it.


Mojo said:


> Dude,
> 
> You know you love the Yellow! You just have to embrace it.
> 
> ...



Hahaha. Embrace the yellow. I'm embracing it with a sander! I've always been more of a olive drab kinda guy. I'm still unsure on the color except I've ruled out yellow.


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## magoo (Nov 6, 2013)

lookin good bro!

All downhill from here.


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## Flatbotm (Nov 7, 2013)

I did a little hatch work on the bow last night.


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## Flatbotm (Nov 11, 2013)

I hauled the Grumman over to a farm pond and did a shakedown fishing trip. 

















The 55# v2 moves this boat around amazing. The remote control is definitely worth the extra $$.


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## Flatbotm (Nov 12, 2013)

My buddy Matt flew in from Colorado to help test out the new boat. Here's the 1st crappie of the day.


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## ifish4redd (Nov 12, 2013)

nothing like a good mess of crappie


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## jasper60103 (Nov 12, 2013)

That's a big crappie!
Good catch.

jasper


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## Flatbotm (Mar 26, 2014)

Thanks fellas! I'm about to get back cracking on this Grumman project. I've got the list of odds and ends to finish up.

1. Aluminum Rod locker for the starboard side of the boat.
2. Hinges and finger pulls for several storage compartments.
3. Tube work and windscreen for side console.
4. Custom homemade bimini top.
5. Coat the interior of the boat with non-slip coating. I decided to not use the nautaulex on this boat.
6. Rid the boat of yellow paint.
7. homemade guide ons for the trailer.

I recently sold my little Crestliner with my endura 40 so I purchased a new endura 50 for the rear of the grumman to go with the 55 v2 on the front.


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