Reattach aluminum keel with solid rivets

[johninalaska]

I was giving a ?great deal? on a very old 10? aluminum skiff. It came with the keel (a formed piece of aluminum about 8? long, 4? wide and 2? deep) and a bag of solid rivets both sitting on top of the boat. I wouldn?t doubt that there are other leaking rivets and problems with the boat but my first task is to get the keel attached to the bottom of the boat instead of sitting on top of it.

I have never worked with rivets but after spending a few hours on the Internet it seems I can install them by hand using a weight at one end of the rivet and a peening hammer on the other end. I am confused when I am installing by hand if I should hit the rounded head of the rivet or the small end.

My other question is: will I need some sort of sealant between the hull and the keel flanges or will the rivets draw up tightly enough to be water tight?

 

[Silvertip]

Re: Reattach aluminum keel with solid rivets

Look at any riveted boat and you will find sealer between the two parts or sheets. You should Google "bucking rivets". There are special tools for this process and you will need help as your arms won't be long enough to hold the dolly on the rivet heat and strick the other end of the rivet inside the boat.

 

[CATransplant]

Re: Reattach aluminum keel with solid rivets

Your job will go much easier if you have a helper. Have the helper hold something heavy and hard like a sledge hammer head against the rounded end of the rivet, which should be inserted from the outside, while you strike the other end with a peening hammer. Make sure all the rivet holes line up properly, and stagger your riveting to make sure you don't get a misalignment as you work. By that, I mean don't start at one end, then just keep going towards the other. Set a couple of rivets near the center of the keel, then halfway to the end on both ends, then the ends, then work between those until all the rivets are in place. If you don't do that, your holes will end up getting out of line.

You will need a sealant of some sort for this job. Since it will be a permanent installation, 3M sealant 5200 will be ideal. Put a generous bead down along the entire length on both sides before starting the riveting. It cures slowly, so you will have plenty of time to deal with the rivets. It will ooze out of the joint, and can be wiped away with a rag dampened with paint thinner. Leave a nice fillet of the sealant in place.

Take your time, and make sure each rivet is tight. The job will require some patience, I guarantee, but it's certainly doable.

 

[External Combustion]

Re: Reattach aluminum keel with solid rivets

Silvertip has you started right. So does CATransplant. You will need a bucking bar which as said can be an ordinary sledge hammer. You will also need a rivet set which is just a steel dowel with a hole on one end slightly larger than the rivet diameter and, to make the job easier, a rivet header which is a steel dowel with the shape of the finished rivet head ground in one end. You can make both tools with a drill press or even a hand drill. You can also buy them at places like Fastenal, NAPA and Lowes.

In riveting, first put a rivet through the hole closest to the center and have your "bucker" place the bucking bar hard against the rivet head. With you on the other side trim the rivet to proper length with a set of flat nippers. Slide the set over the rivet and give it a good whack. What this does is draw the plates close together. Then use the ball of a ball peen hammer to flare the head of the rivet. Hit the rivet with light to medium blows slightly off center. The head will swell quickly. Before it is at the finished diameter switch to the header and finish with firm to heavy blows. Stop as soon as the rivit head is the final shape. It is easy to over flare and stretch the plates, so stop as soon as it looks right.

A four to six ounce ball peen hammer is just about right for aluminum rivets up to 1/4 inch in diameter.

If the rivets seem the slightest bit hard, throw them away and get new ones that are a fresh batch. Some aluminum rivets are designed to age harden. You probably won't encounter the type that have to be refigerated the whole time before you use them, but know they are out there. Sometimes the throwaways from aircraft plants make their way into others tool boxes just to make life misersable for the unsuspecting.

Work from the inside of the rivet pattern to the outside like you would torque the headbolts on a head.

I have done some boat repairs, but a whole lot more boilers. I learned from an aircraft mechanic. I'm glad he showed me how simple it is.

Have fun.