View Full Version : 88 ProStar Rear Seat Rebuild

06-05-2013, 08:08 PM
I had two goals with this project: re-build the 25 year old rear seat and create more storage space in the boat. This generation ProStar is sorely lacking in space. Yes, there's storage in the closed bow, but it's cramped and difficult to access. For a family with two young boys, such limited storage is not acceptable.

The original seat was in rough shape. I didn't take a picture of the cushion before I began, but the vinyl was cracked, split, torn and generally falling apart. The foam in the base was pretty well thrashed as well.

The Styrofoam base had some holes in it and the wood core was rotting. I wasn't too concerned as I was going to be discarding this section of the seat.

Chalk line to mark the cut. I just used a jigsaw to cut the foam. Went smoothly. The chalk is about 6 inches from the bottom of the base.

The point of no return...

Cutting the base off, I lost a lot of structural integrity to the back and sides. I was able to recover most of it by cutting a 'U' out of 3/8" plywood. I used Liquid Nails and 1/4" dowels to glue and pin the plywood to the seat back.


I know it looks bad, and I would have preferred to buy new skins, but that wasn't in the budget. I started cutting down the seat cover and reattached it to the seat back. It looks pretty rough in this picture, but once the seat is in position, you can't really tell.

Completed seat back. A wrinkle or two, but I can live with it.

Next step, the new seat base.

06-05-2013, 08:15 PM
Can't wait to see how your project comes out. Had to replace the wood strips in my rear bench. Used the polystyrene lattice strips from Lowes with very good results. No more rotting.

06-05-2013, 08:30 PM
OK- the next step: seat base and creating more storage. I took a cue from this post (http://www.mastercraft.com/teamtalk/showpost.php?p=883165&postcount=6) about creating more storage under the rear seat by building in a compartment. I enlisted the help of a contractor buddy and creative genius. He had some redwood left from a project, so we ripped it to 5" and built a basic rectangular frame.

With the frame giving us a new height for the seat base, we cut a piece of 5/8" plywood to size and then cut out two large access panels. The plywood was then coated in West System epoxy for strength and waterproofness.

Next step- cushions. I picked up some foam at the local foam shop- I went with a 5x5" high density foam for the front of the cushions and two layers of 2" foam for the main seat. I used a high density foam on top with a medium density underneath. On the left side of the seat is the leftover foam so you can see the different thicknesses and layers.

I went with three cushions, two over the storage access holes and one in the center of the seat that would cover a carpeted step area. I had managed to borrow an industrial sewing machine and had enlisted a friend to help with sewing cushions, but we couldn't get the machine working. The backup plan was we glued the foam to a plywood base (epoxied both sides first) and then wrapped the vinyl over and stapled it. When I say wrapped, we literally wrapped the foam cushions like you'd wrap a present. Turned out well though, I think.

Next step was carpeting the seat box and seat base. That was relatively straight forward. I used marine carpet I sourced through West Marine. I discovered that the original seat back is angled, and under pressure would ride up against the back of the boat. My solution was to cut two pieces of redwood, carpet them and then screw them down to the seat base. You can see those in this picture.

With the modified seat back in place. Looks pretty good, I think.

Center cushion removed to show step area.

This is a view of a cushion bottom. Each cushion has it's own base. I saved the plywood from the two access panels, epoxied both sides, then screwed them to the bottoms of the left and right cushions. Those pieces are sized so they're a tight fit in to the access panels, which holds the cushions in place. The center cushion is pretty well wedged in there, but I'll probably remove all three cushions when trailering.

Completed seat with all cushions in place.

I haven't had the boat out yet (week long trip coming up, we leave Sunday), but based on sitting on the seat and making vroom-vroom noises, I think it'll do the job. Currently in the storage space are two anchors, a 100' anchor line, a 50' anchor line, my tool/spare parts box and my flush hose. Still more room for ski lines and whatnot if needed.


06-05-2013, 10:04 PM
Great work! Thanks for the pics and how-to as this is something I have been wondering about.::cool:

06-05-2013, 10:57 PM
SSMoose- feel free to ask questions. I'll help out if I can. It was not as hard as it looked. I did a lot of thinking about what I wanted the seat to look like and how to accomplish that, so it seemed to go pretty smoothly.

06-05-2013, 11:16 PM
Wow! Great work and great ideas in this project.

I have often thought about a similar setup but I have not had time to tackle it. I bought an extra used rear seat to try my ideas without destroying the original. This gives me some motivation and I may use some of your ideas if you don't mind.

06-06-2013, 04:01 PM
It was a pretty straight-forward job. There are a couple of little things I discovered:
-I used a jigsaw to cut the Styrofoam seat. When you're cutting the seat back, the saw foot needs to be angled to compensate for the angle of the seat back so you get a nice cut. I didn't do this, and had to fill in with foam shims and construction adhesive.
-That same angled seat back, when in place, will rise up if you lean on it (when it's in the boat). I used those carpeted wooden blocks to keep it from moving.
-I found that the seat base I made wanted to slide around on the carpet. I screwed a couple of blocks on the front corners that wedge it in place. The wedges aren't visible once the base is in position on the boat.
Those are the big things I remember. The rest of it is just taking your time and thinking about what you want it to look like.
Good luck!

06-06-2013, 05:54 PM
Looks good Greg!

06-06-2013, 09:32 PM
Thanks, Tim! I'm pretty happy with it. Some of the more MCOCD folks might not appreciate my quickie upholstery job, but if it holds up for a couple of seasons, I'll consider it a success!

06-08-2013, 10:59 AM
I like it! I have been thinking about doing something like this for my '83. The only concern is do you feel the seat being too shallow when sitting in it now?

06-08-2013, 03:20 PM

I wish I you had posted this 2 weeks earlier......I have been working on the same fix but your documentation is awesome!
My wife recommended I cut the Styrofoam seat with an electric carving knife, it cut like butter and easily maintained the chalk line. I took out a 4 inch section (from the center) in order to preserve the curvature of the top of the back rest. We reconnected the 2 pieces with carpet glue and wood dowels. (Suggested by my wife also)
We added a 1/2 marine grade plywood base to the bottom of the Styrofoam to create a stronger base.
we used Lowes paint sticks to replace the wood staple strips on the Styrofoam, perfect match on the size and they were held in with liquid nails.

We used plastic cups to measure the height so we could build pvc pedestals (6) to use as feet.

Our intention was to get the seat off the floor and create some (not much) under seat storage.

I'm going to try and post some pictures of the process and a final when I can get one.


06-09-2013, 02:28 AM
Roush- You definitely sit up higher. In the old seat the top of the seat would hit me in the lower shoulder blade area. Now it's closer to the lower rib area. My wife is a little concerned about it, but I have a feeling that by the end of the summer, the foam will have compressed a bit. I'm expecting about a 1/2" loss in seat height, which should make it about perfect. If it's still a problem, I might pull the skins and cut out some foam, but I really don't think it'll be that bad.

Lotus- that's a sweet looking interior combo. I like how you saved the seat base, but mine was too far gone. The cushion was complete junk, at least as far as the skin went. I like your idea of having the area under the seat open, allows for storage of larger items. I might think about cutting out part of the front, to allow for storage of larger items, but for now this will work. I'm also thinking about maybe putting some LED lighting under the bench, for night time visibility in the walk ways.

Thanks for the positive feedback! I was a little unsure when I started this project- had a vision, but wasn't sure I could pull it off. Glad it worked out. I think next, I'm going to replace the plywood in the ski lockers.


06-09-2013, 10:40 AM
When I had my 83 in the upholstery shop I had them customize my rear seat too. Although I didn't have the storage area, being able to remove the middle cushion was a huge benefit.

06-09-2013, 10:49 AM
When I had my 83 in the upholstery shop I had them customize my rear seat too. Although I didn't have the storage area, being able to remove the middle cushion was a huge benefit.

Very nice work.:cool:

06-12-2013, 02:20 AM
That looks sharp. Your efforts paid off.

11-20-2013, 07:39 AM
Thanks for posting in the other thread! I couldn't find your original thread until now.

06-27-2014, 03:17 AM
Wow! Great work and great ideas in this project.

I have often thought about a similar setup but I have not had time to tackle it. I bought an extra used rear seat to try my ideas without destroying the original. This gives me some motivation and I may use some of your ideas if you don't mind. where did you purchase your extra rear seat from?

06-27-2014, 11:56 AM
Found it on Craigslist. An area ski team was not using it in their boat and had it for sale.

07-08-2014, 03:25 AM
what keywords did you use to find it? I've been looking for one for a while now for my 1982 and can't seem to find one anywhere.

07-08-2014, 03:26 AM
Or if you could could you post the dimensions of the rear bench seat on here so i could possible fabricate one myself