Pedestal Seat in a Jon Boat?

[Clint KY]

I have a 1648 with a large front deck with foam floatation under it. I want to mount a pedestal seat on that deck that I can remove so I can retain the use of the deck while fly-fishing. I have looked at the standard Pin type Steel Base Plate but am at a loss on how to mount one. I have seen Nutserts that I can probably find someone locally who has the insertion tool, but don’t think the thin aluminum alone will support the weight of me if I were to lean over a bit. Anyone have an idea or suggestion on how to do this?

 

[redbug]

If it were me I would drill out the hole where the center of the base will mount
remove some of the foam from under that section then use large washers even thinking about making them myself to help spread the weight and stress that the seat will put on the deck

 

[jigngrub]

Clint KY » 02 Mar 2014, 10:08[/url]"]I have a 1648 with a large front deck with foam floatation under it. I want to mount a pedestal seat on that deck that I can remove so I can retain the use of the deck while fly-fishing. I have looked at the standard Pin type Steel Base Plate but am at a loss on how to mount one. I have seen Nutserts that I can probably find someone locally who has the insertion tool, but don’t think the thin aluminum alone will support the weight of me if I were to lean over a bit. Anyone have an idea or suggestion on how to do this?

This is a pretty easy project to do.

Your concerns for the small base plate and thin aluminum decking are well founded, an installation of the pin type base plate fastened directly to the decking wouldn't last long... especially with only 6 fasteners securing it to the thin aluminum decking.

Pedestal seat bases are primarily designed to be fastened to a plywood deck, and that's what I'd do. You can either deck your entire front deck with plywood or make a larger base out of plywood for the pedestal base to fasten to.

Option A:
For a clean flush installation I would cut a piece of 3/4" plywood the size of the front deck and fasten the pedestal base to the plywood with stainless steel 1/4-20 bolts and T-nuts:

If you use 3/4" plywood with a 1/4" thick pedestal base a 1" long bolt should come out flush with the bottom of the decking, if the bolts protrude below the decking you can mark them and cut them off.

After you get the ped base installed on the plywood, remove it and lay the decking in the boat and mark and cut the hole for the center pin in the aluminum decking. Secure the plywood decking in the boat with rivets or screws preferably through your deck framing members and reinstall the pedestal base.

Option B:
This uses a smaller piece of plywood, a 16"x16" or maybe even a 12"x12" piece (the bigger the better though). Secure the pedestal base to the plywood and the plywood to the deck in the same manner described above. The larger plywood base will distribute the weight and forces of someone sitting in the seat over a larger area and you'll be able to secure the plywood to the boat with more than just 6 fasteners, I suggest fasteners installed around the perimeter on at least 3" centers or closer.

Of course you'll want to seal and protect your plywood with either installation, I suggest using a non-slip paint the same color as your boat.

If you choose option B you'll want to bevel the edges of your plywood on a 45 degree angle.

 

[muskiemike12]

What I would do is get a 18" length of 1/4" x 2" flat stock aluminum. Use a hole saw to cut the hole for the pin base. Put your base on the deck where you want it and trace the 6 holes in the base onto your deck. Drill these out with a 7/32 bit. You will also drill out four, 2 on each side 1/8 holes. You will want to also counter sink the 1/8 holes. Placement of these holes is not critical, as these will be used to hold the flat stock in place.

You are going to use the flat stock as a backing plate. You will need to cut the flat stock into two 9" pieces. Take the flat stock and hold it up under the holes, on the bottom side of the deck, and trace the holes onto the flat stock. Make sure you remember the orientation of the flat stock when you go to reassemble. Drill those holes out again with a 7/32 and 1/8 bit. Reinsert the flat stock on the bottom side of the deck and align the holes back up, hold in place with four 1/2 x #8 self tapping screws, this will be to hold the backing plate in place.

Next you will need a 1/4-20 tap. Tap the holes, put oil on the tap to make tapping easier. Line the holes up on the base and fasten with 1" 1/4-20 stainless screws.

 

[Clint KY]

jigngrub » 04 Mar 2014, 09:59[/url]"]
Pedestal seat bases are primarily designed to be fastened to a plywood deck, and that's what I'd do. You can either deck your entire front deck with plywood or make a larger base out of plywood for the pedestal base to fasten to.
Option B:
This uses a smaller piece of plywood, a 16"x16" or maybe even a 12"x12" piece (the bigger the better though). Secure the pedestal base to the plywood and the plywood to the deck in the same manner described above. The larger plywood base will distribute the weight and forces of someone sitting in the seat over a larger area and you'll be able to secure the plywood to the boat with more than just 6 fasteners, I suggest fasteners installed around the perimeter on at least 3" centers or closer.

The obstacle here is that the deck is not perfectly flat. It curves up towards the bow about 2/3rds the way from the back of the deck to the bow. I could could cut saw kerfs in the plywood and form it to fit the deck.

I have considered a version of your Option B. I may make a removable base of plywood that covers the flat portion and secure it somehow at the sides. The challenge here is to secure the plywood base in a way that I can remove it without leaving bolts or other hardware sticking up for me to trip over when the base is not in the boat.

muskiemike12 » 04 Mar 2014, 10:55[/url]"]

You are going to use the flat stock as a backing plate.

The obstacle to this plan is that the deck has foam under it for flotation. I considered getting long screws and going all the way through the foam and putting the backing plate under the foam as I do have access to the bottom, but it still leaves the pedestal on the thin aluminum of the deck.

 

[muskiemike12]

Just dig out some of that foam and it shouldn't be an issue.

 

[jigngrub]

Posting pics of your boat and the bow area would help us see what you have to work with and would give us a better idea of how to help you.

By your most recent description, I would install the plywood on the flat area only if it's a large enough area.

 

[Clint KY]

I am not willing to dig out any foam from the deck as it and the foam in the rear seat is the only flotation left since I removed the center seat.

I had intended to post pictures but this freak March snow storm makes that problematic right now. And the deck is HUGE so I think I will have enough room to do the "partial" plywood idea.

Thanks for all the ideas. I hope to get this figured out before I start so I don't have to re-do the project once done.

 

[jigngrub]

Clint KY » 36 minutes ago[/url]"]I am not willing to dig out any foam from the deck as it and the foam in the rear seat is the only flotation left since I removed the center seat.

You don't have to worry about removing foam now because not enough floatation is the same thing as no floatation at all.

The factory installed floatation in an aluminum bench boat is minimal and just enough to keep the boat afloat if it swamps or fills because of a hull breach, removing 1/3 of this foam will send your boat to the bottom in either one of the 2 cases.

 

[gonefishin 50]

I just mounted pedestal seats to my boat. I drilled out all holes and just enough foam for the base to lay flat. I took 1"x 12", 1/4" thick flat steel. Mounted under the seat. Took 7" bolts and mounted the base plate that way. I hope that makes since.