Alumacraft SuperHawk CS build thread.

bman2895 · Aug 26, 2024

I picked up a 91 Alumacraft SuperHawk CS. It's a 15ft single console. "Crappie boat" as Alumacraft calls it. But my intentions are primarily bass fishing. It's was cheap. Like 200$ cheap. But it is pretty much completely stripped. No decks on it. No carpet. No seats. And the transom wood is rotten. So primarily I'm digging into the transom area now. But I do have some questions about when everything goes back in.

It has a 40hp Evinrude. And its in great shape. Runs good. No Tilt and trim. But looks easy enough to add.

My biggest questions are this.

I've been taking the rivets out slowly to get into the transom. Seems the only way in is from the inside. How do I determine what size rivets and length I need to go back in? If I go off a drill bit a 9/32 is snug in the holes. I've done something similar before on a smaller aluminum boat and just went back with bolts and rubber washers and it was fine, but id like to do this one back with rivets. And what tools are recommended to do it right.

Most of the foam has been removed from this boat. I did get the 2 part marine foam from the seller when I bought it. But I've also heard of people removing the foam and not replacing it on aluminum boats? I figure it necessary in the back on each side.

Ray Clark · Aug 26, 2024

I can't talk to the rivets.

The boat being essentially stripped means you're working with a "clean sheet". The foam and decks being already removed saves you some work. That's good.

I've never heard that aluminum boats don't need flotation. If that was the case, the manufacturers wouldn't put it in. If it was me, I'd use the two-part foam you have. If that's not enough, get some inexpensive extruded polystyrene from the home center to make up the difference.

Gilby · Aug 27, 2024

When I removed mine I sacrificed an old chisel to pop the rivet head off from the outside. Just being careful to keep the chisel flat to the transom as to not gouge the aluminum and it worked out pretty good. I ordered rivets the were about 3/4' longer than the transom is thick and a rivet hammer to fit my air hammer. Take note of which style rivet you get and get same style hammer as there are several different shapes. I then used on old flat face hammer head I have lying around, (probably about a 4 pound or so) and a buddy would hold the hammer while I used to air hammer to pound the rivets into place and smash them (i'm Sure there is a more proper term other than smash them). I also coated each hole and rivet with 3M 5200. Wear ear plugs!! Its a super loud job

bman2895 · Aug 27, 2024

Thanks for the tips. Yeah I'll for sure put the foam back in the rear compartments. Though I'll have to do some research on using that foam.

I've been using a chisel and shearing the flat side of the rivet from the inside and knocking them out the other way. Is knocking them in from the outside preferred?

thill · Aug 27, 2024

Gilby said:
When I removed mine I sacrificed an old chisel to pop the rivet head off from the outside. Just being careful to keep the chisel flat to the transom as to not gouge the aluminum and it worked out pretty good. I ordered rivets the were about 3/4' longer than the transom is thick and a rivet hammer to fit my air hammer. Take note of which style rivet you get and get same style hammer as there are several different shapes. I then used on old flat face hammer head I have lying around, (probably about a 4 pound or so) and a buddy would hold the hammer while I used to air hammer to pound the rivets into place and smash them (i'm Sure there is a more proper term other than smash them). I also coated each hole and rivet with 3M 5200. Wear ear plugs!! Its a super loud job

Good choice, popping the heads off the rivets. That is the best way, in my opinion, rather than trying to drill.

3/4" longer? Did you cut the tails down to 3/16"-1/4" long before "smashing" them? If you didn't, did they want to fold over and break, rather than expand? Just curious

Gilby · Aug 27, 2024

thill said:
Good choice, popping the heads off the rivets. That is the best way, in my opinion, rather than trying to drill.

3/4" longer? Did you cut the tails down to 3/16"-1/4" long before "smashing" them? If you didn't, did they want to fold over and break, rather than expand? Just curious

They may not have been that much longer. It's been over a year ago now since I did my transom. But they all fastened as they should have during the process and smashed down correctly and are holding tight. Apologies if that number is way off.

bman2895 · Aug 28, 2024

So question. How do I accurately determine the diameter of the rivet?

Stand Up · Aug 28, 2024

I would use a drill bit index that has bits in 1/16 inch graduation. Insert the drill end of the bits into the hole that the rivet was in until you find the one that fits perfectly. Then you know the size. If you're drilling out an old damaged rivet hole, use a bit that will just allow the hole to be corrected and use that bit for sizing the rivet. There are different diameters and lengths of rivets as well as different types of material used to make the rivet so do a bit of study beforehand so you know what is available first.

bman2895 · Aug 28, 2024

Honestly I'm leaning towards just using stainless steel hardware in the back of the transom and just using rivets for the bottom of the the braces and the side brackets

bman2895 · Aug 28, 2024

Those longer 2+" solid rivets seem like a trick to find.

thill · Aug 28, 2024

Grainger?

bman2895 · Aug 29, 2024

There is one not too far from me. I may give them a call and see

bman2895 · Aug 29, 2024

So I'm shopping plywood for the transom. Of course no where local has marine grade. I've been reading pressure treated is a no no. So what exactly do I need to buy and epoxy? Is this what I'm after? Glue together with tite bond and then coat in epoxy. What epoxy does everyone use?

LDUBS · Aug 30, 2024

As long as it is rated for exterior applications you are good to go. Titebond III is supposed to be waterproof and should work for gluing the two panels together. Instead of running a bunch of zig-zag beads, spread it to cover the entire surface of the ply. Of course, use plenty of clamps or weights until the glue dries. The two pieces of ply will want to slide all over the place until the glue grabs. I typically glue them together before cutting to final size. .

I have used penetrating epoxy to seal plywood with good results. TinBoat Member @thill successfully uses Thompson's Water Seal. Others use paint. You can also search these forums for "Old Timer's Formula" which is a mix of one part each of spar varnish and boiled linseed oil, and two parts mineral spirits.

bman2895 · Aug 30, 2024

Well got the transom out finally. 45 rivets total. And ran into some concerning issues. Mainly some corrosion in the transom area of the boat. Some light pitting in some areas. Some pretty deep. Some actual pinholes. I'll attach some photos. So what's the course of action for this? Is it scrap? Jb weld or some other epoxy to seal in the pitting?

bman2895 · Aug 30, 2024

Wider angle

bman2895 · Aug 30, 2024

Also. There is no one around to replace the transom skin. No real boat shops around here that tend to mess with anything that isn't brand new. I'm also unable to weld aluminum. So will need recommendations with those things in mind. I'm also not opposed to a "doing the wrong thing the right way" kinda fix as well.

davidj65 · Aug 31, 2024

bman2895 said:
So I'm shopping plywood for the transom. Of course no where local has marine grade. I've been reading pressure treated is a no no. So what exactly do I need to buy and epoxy? Is this what I'm after? Glue together with tite bond and then coat in epoxy. What epoxy does everyone use?

Technically Titebond 3 should work, but it is difficult to spread it evenly and apply sufficient clamping pressure. Epoxy is easier to clamp properly.

bman2895 · Aug 31, 2024

What kind of epoxy?

davidj65 · Aug 31, 2024

A regular set epoxy. Check out the System 3 products. Different hardeners have different working temperatures, working times, and cure rates. 2:1 ratio for all of it. Not cheap but you can thin it and also use it to seal the outside of the transom.

Franklin claims Titebond 3 is good for exterior applications, but it wouldn't be my first choice. I doubt it is long term for constant submersion. In any case, if you did use it for a transom and enough water go t in to compromise the joint, then you have other problems, I would say.

(Mind you, I have done no transom work, but I do woodworking professionally and so I am decently familiar with wood adhesives).

Alumacraft SuperHawk CS build thread.

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