1990 Grumman 14SS

[Zip]

Like I posted last week I got this boat and already started to go to work. This thread is just a progress thread. I got a 1.5 year old and work opposite shifts as my wife so it probably will be updated slowly. I have been researching quite a bit, but will ask questions in this single thread to keep it all together. I am completely new to rivets (but they seem simple enough).

Either way, just started taking out the floors, and the got the transom removed, rotted of course and will be working on getting the wood sealed and cut for now. While removing the motor, the transom cap snapped in half (it seemed to have been stuck to the outboard lol) so already one piece broken, not sure how I will tackle that just yet.

Quick questions - what is the recommended thickness for floor/deck plywood? Also, should I use the same type of wood for deck as the transom (not pressure treated?).

 

[airshot]

The cracked transom cap could be repaired by welding with a patch on the underside, depending on condition of the material.....or some folks just use angle aluminum and create their own. Have saw some with a single layer of angle and some have used two layers of angle. I can remember those days where the playpen was moved into my shop area so I could get something done....lol

 

[Zip]

Thanks, I don't have any experience welding so I might need to fabricate with that angle aluminum. Or maybe thin it down and put some angle aluminum over just the 8in center where the motor would mount to? Not a main concern just yet but certainly will need to figure it out. Going to go out and get some paint thinner and that heavy duty riveter from HF today, and start removing more of the floor and brackets when I get home today.

 

[LDUBS]

"Quick questions - what is the recommended thickness for floor/deck plywood? Also, should I use the same type of wood for deck as the transom (not pressure treated?)."

In general, I would use 1/2" exterior ply for the floor. Exterior ply will also work great for the transom. Layer it up to the thickness needed for your transom. Note that marine grade ply (a terrific product) is not really needed for this application. Just like marine grade, exterior ply also uses waterproof glue. The basic difference is exterior grade ply will have some voids.

I look forward to watching your progress.

 

[Zip]

Perfect, thanks. Almost cleared out the inside of the hull by drilling out all the rivets, will get pics up once I do!

 

[Zip]

Quick question regarding rivets. I am going to place an order and wanted to make sure for the solid rivets, (im sure my size is 3/16th for the thru-hull rivets) would be:

3/16 X 5/16 BRAZIER HEAD 2117T4 ALUMINUM RIVETS​

Is 2117T4 the standard? I read they are stronger than the 1111F rivets. And Brazier head is the correct "standard" head?

Lastly, for the closed end blind rivets (attaching rails and stringers to bottom of the hull), do I want an aluminum mandrel or a stainless one? Ive been reading different opinions on the dissimilar metals. Anyone got a take on this?

 

[Zip]

Got the hill cleaned out. Definitely added a few holes from not drilling rivets straight thru. will deal with that later. Next up is borrowing a pressure washer for the inside. Some of the benches were riveted more than I thought to the bottom. Also bought the wrong 1/8th closed end blind rivets, looks like they are 3/16. Here’s a pic.

 

[Axhammer]

Quick question regarding rivets. I am going to place an order and wanted to make sure for the solid rivets, (im sure my size is 3/16th for the thru-hull rivets) would be:

3/16 X 5/16 BRAZIER HEAD 2117T4 ALUMINUM RIVETS​

Is 2117T4 the standard? I read they are stronger than the 1111F rivets. And Brazier head is the correct "standard" head?

Lastly, for the closed end blind rivets (attaching rails and stringers to bottom of the hull), do I want an aluminum mandrel or a stainless one? Ive been reading different opinions on the dissimilar metals. Anyone got a take on this?

When you said Solid Rivet, I believe you meant to say Closed Rivet.

A solid rivet must be “Bucked”, which is a process of mechanically deforming or expanding the end of the rivet. When you drive a solid rivet, a pneumatic rivet gun is used, along with a heavy chunk of steel called a bucking bar. The rivet gun drives the head end using a rivet set that matches the rivet head style, and the bucking bar drives the shaft end, the process forces the diameter of the rivet to expand and fill the hole, and then the shaft end will deform, and flatten out, forming the Bucktail.

2117 is the series, which tells you the composition of the rivet. The 2 indicates Copper as the major alloy element. The 2117 or AD series is common in aircraft assembly, but I’m not sure what is commonly used in aluminum boat assembly. Maybe someone with more knowledge will chime in. The 2117 is definitely stronger than the 1111, 1 indicates aluminum.

The SS mandrel rivet will be much stronger than an aluminum mandrel Rivet.

Dissimilar metals will corrode when in contact, and exposed to moisture. SS and aluminum get along pretty well, when compared to other combinations. I believe the SS mandrel will be best for your application.

Brazier heads seem to be the head style commonly used to assemble aluminum boats. My 1648 and 1751 both use brazier head rivets.

 

[Axhammer]

When an aluminum boat is manufactured, solid rivets are used because they are superior in strength & longevity.
If you drill out solid rivets during your overhaul, and then reassemble using blind rivets, AKA pop rivets, you are sacrificing strength for convenience, because it’s easy to slap in some pop rivets, vice bucking some solid rivets.

One method to get back some of the lost strength is to use adhesive or glue, while reassembling your boat.

I suggest using 3M 5200 sealant on each rivet, and or part interface. Dip or brush a small amount of 5200 on the rivet shaft, and in each hole, before installing each rivet. If you are riveting a flange together, then apply a little 5200 to the flange. It sounds like a lot of extra work, and messy, but this will provide superior strength. This is called a “Wet Installation”.

I suggest you wet install every part that is a permanent install.

5200 will create a watertight seal, provide a barrier, to help the dissimilar contact, and it will be much stronger.

 

[Zip]

Thanks - I was in fact referring to solid rivets. I am going to buck them back in for any thru hull river work. Blind closed end closed for the bench seats and to river then back to the floor rails.

I was thinking about using some g-flex or some of that Alcoa gutter seal on the rivets instead of 5200 since I remember that thread recently showing some of the corrosion 5200 caused.

 

[thill]

Gutter seal is excellent stuff, in my opinion.
Thumbs up on solid rivets.
Drill the 1/8" to 3/16", if space allows.
Good plan, so far