Seat base install questions

Should I use a 12x12" plate to help strengthen my seat bases? The ones in right now are kind of wobbly when I sit in them. I know Sea Ark does this with .125 tread plate to strengthen the bases.

Which is the best way to secure the bases? Should I use a bolt, washer and nylon lock nut or bolt, lock washer, and a regular nut?

I'll be sure to use stainless steel hardware.

What material and thickness are you going to be mounting them in?

Welcome Aboard, Seth! Will the 12"x12" piece you are talking about be mounted under a bench seat or the deck as a doubler plate? I'd go with stainless bolts, large washers, and the ny-lock nuts. Have any pics of the project to post? 8)

Here's a few pictures of my rig. I bought it last June 2007 for $1500. It's a 1648 welded F&F with a 50hp Yamaha jet drive. I'm not sure of the thickness of aluminum that decks are made from, but it's not very thick and definitely not .125. I had planned on just mounting the bases to the 12x12 plate and then securing the plate to the deck. Would it work better if I installed the plate below the deck and just make sure the base bolted through the plate?

Here's some pictures of the boat the day I brought it home.

Front deck

Middle

Back Deck

Whole Boat

Motor

off topic... but nice boat, good deal too

Would it work better if I installed the plate below the deck and just make sure the base bolted through the plate?

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Morning Seth!,

I'm at work right now and can't see the pics you posted (blocked here at work), but if it's accessible I would mount the plate under the deck and insert the bolts through the seat pedastal base, the deck, and then use large washers (sometimes called Fender washers) and nylock nuts. I'll checkout the pics when I get home today. 8)

Ok I will be sure to mount it underneath the deck then. I'm sure that will look neater anyways. What thickness plate do you think I should get? Would .125 be enough or do you think I should go with .250? I think it was like almost $40 off metaldepot.com for a 12x12 of .125. Metal ain't cheap!

1/8" should work okay, with washers between the plate and the nylock nuts. If possible, I'd leave some "meat" around the edges (corners) of the new doubler plates where the holes will be drilled..

You mention using the 12 by 12 because the base was wobbly, not because the nuts were trying to pull through. If it was because the nuts were coming through, the 12 by 12 would be fine. But, since you will only be gaining 2 - 3 inches on a side over the 6 by 6 or 8 by 8 the seat mount is, I would think you would want a bit more than 12 by 12, as it will still rock the deck a bit. Try closer to 18 by 18, or if you just lean back on it, 10 or 12 by 18, and just put it longitudinally.

.125 sheet should be just fine with this. I see no reason to use .25 plate, unless you just had some on hand. .1875 might be good, if you don't feel safe with the .125.

You can do better than that as far as pricing. Go to ebay, and type in .125 aluminum, or aluminum sheet, or aluminum plate or whatnot on there. Amazing the number of drops sold on there fairly cheaply. Most are smaller than 18 by 18 square, so the factory that has them cannot use them. May have to settle for some thicker stuff, but if you get into .25 (I have seen plenty that is less), you can thread it, and not need nuts.

Ok, I been thinking about this some more and since I can remove my decks totally and work on the from underneath, would I be better if I just added some more angle to the frame so that the base holes will line up with the frame? It looks like most guys just build there frames to where they secure the bases to them and don't use a plate.

...May have to settle for some thicker stuff, but if you get into .25 (I have seen plenty that is less), you can thread it, and not need nuts.

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All good points bb1, however, if something happens to cause the bolts/screws to pull through and strip the threading, then that stage of the project would be back at square one, with the possible need to use washers and nuts afterall. Just a thought.

Seth,
Perhaps there might be other members who have an idea or alternative that bb1 and myself have not thought of.

Come on guys, a little brain-storming needed here

I'll be using a through bolt, back up washer, and nylon lock nut either way. That's what the seat base recommends anyhow and seems to be the preferred way.

Do you think I'd be better off just adding some more bracing so that the base holes line up with the braces below the deck? Whoever made the decks didn't do this before and I don't know why since it seems that's what most guys do when they make decks.

Waterwings said:

All good points bb1, however, if something happens to cause the bolts/screws to pull through and strip the threading, then that stage of the project would be back at square one, with the possible need to use washers and nuts afterall. Just a thought.

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Points taken, however, I will say this. My trolling motor is bolted with the exact method. It has 4 5/16 bolts threaded into 1/4 inch aluminum. Due to the shape of my bow, I can only use 4 of the 6 mounting holes in the MK trolling motor. Those that have these bow mount MKs know that the bolts aren't but about 5 inches apart lengthwise, and less than 4 crosswise. Also, the one thing I am most abusive of is my trolling motor. Everything else, I take perfect care of, but I am he!! on trolling motors, at least ones on bass jons (I only hurt them while bass fishing, basically, and I am too scared to take glass rigs into tighter cover) I have forgotten to stow it when taking off (and I slam it to WOT just as soon as the motor is warmed up, so there is no slow period for me to notice it down), and it really bounces the boat around. Also, I have been idling around with the trolling motor down (I do that a lot) and slammed it into rocks, plus I slam the trolling motor into every rock I can, it seems, and that mount has held up just dandy. It would take a LOT of force to pull threads out of there. And, if he does, just drill the aluminum out, and put fender washers/nylocks down there. Just buy your bolts 1/2 inch too long to allow for that, if you feel that is a problem.

BTW, I won't be selling this trolling motor when I replace it. I take too much pride in the quality of what I sell to give something one I had done that to. If you see me with a trolling motor for sale, it will not have been one treated like this, as I probably hadn't gotten my hands on it yet, or it was on a boat that I don't take to the river, where there are rocks and crap for me to hit real shallow.

Seth said:

I'll be using a through bolt, back up washer, and nylon lock nut either way. That's what the seat base recommends anyhow and seems to be the preferred way.

Do you think I'd be better off just adding some more bracing so that the base holes line up with the braces below the deck? Whoever made the decks didn't do this before and I don't know why since it seems that's what most guys do when they make decks.

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That is a viable option. However, if your deck is strong enough otherwise, with no flexing, and the only problem is the seat base, I wouldn't bother. But, if there is no structure in the vicinity, and it is wobbly other times, by all means add some structure.

Ok I will take a look at it when I get the decks off and then add a few braces for the bases. The bases are pretty sturdy for myself and most others that I fish with, but a few of my "bigger" friends might have problems. I never heard them say anything, but I figure since I have them off I'll just add the bracing and not worry about it.

I will posts some pictures up when I get the decks off the rest of the way. Hopefully I'll get that done this weekend. Just depends if I feel like working on the boat when it's 20 degrees outside. :x