Here's how I fixed the cracked cushion bottoms on my 242LS

[Leadfooty]

Like many, I found the bottoms on some of my cushions had cracked. In my case it was from the previous owner, but given the light weight substrate and no reinforcement as is found on other boats, my guess is that it's a matter of time for most owners. Adding to concerns is that there are no longer any replacements for some of the cushions on my 6-year old boat. That is truly poor after-the-sale support for such an expensive vehicle. You listening Yamaha?

So after looking at several options and other solves on jetboater, I decided on reinforcing the bottoms by using supports made from polyethylene sheet. Most recommendations for Starboard suggest mechanical attachment, but there are several people who've had success w/ JB Plastic bonder. I decided since some of the cracks are clear across the seat-bottom to use both approaches. Here's what I did:

I bought the following:
• two tubes of JB weld plastic bonder
• a few dozen #8 x1" stainless screws
• a sheet of Seaboard High Density Polyethylene Sheet, Matte Finish, 1/2"

Then:
First I made reinforcement templates out of craft paper sized to fit inside the storage opening and transferred them to the plastic sheet. I cut the sheet with a table saw and radial arm saw and chamfered the facing edges w/ 1/4" router bit (I think I'd use a 1/2 bit if I did it again). Then I pre-drilled holes at about every 2" and countersunk the holes. Polyethylene is very easy to work with and cuts and drills nicely though it makes a giant mess of non-organic "sawdust" that gets everywhere.
I then taped the reinforcement plates to the seat-bottom and pre-drilled pilot holes. I'm not certain you need to do this, but I didn't want any cracking, particularly near the existing cracks. After that I used a torch to surface condition the polyethylene sheet and the seat bottom (which is clearly NOT the same kind of plastic, it singed when I heated it) to ensure good adhesion.
After that it was simply a matter of glueing and screwing, making sure i got a lot of the glue deep into the cracks. One more thing I did was some of the light blue "cushion-stops" on the bottom of the cushion were loose and the threads of the screws were beginning to strip. So I used some #10 x 1 1/4" screws to replace the #8s and it tightened them right up.

The result appears to be pretty sound. The cushions themselves do feel significantly heavier than prior but there is no flex in the bottom at all now. We'll see how long it lasts and if all goes well, I may do a few of the others as precautions.

See photos for results:

 

[swatski]

Like many, I found the bottoms on some of my cushions had cracked. In my case it was from the previous owner, but given the light weight substrate and no reinforcement as is found on other boats, my guess is that it's a matter of time for most owners. Adding to concerns is that there are no longer any replacements for some of the cushions on my 6-year old boat. That is truly poor after-the-sale support for such an expensive vehicle. You listening Yamaha?

So after looking at several options and other solves on jetboater, I decided on reinforcing the bottoms by using supports made from polyethylene sheet. Most recommendations for Starboard suggest mechanical attachment, but there are several people who've had success w/ JB Plastic bonder. I decided since some of the cracks are clear across the seat-bottom to use both approaches. Here's what I did:

I bought the following:
• two tubes of JB weld plastic bonder
• a few dozen #8 x1" stainless screws
• a sheet of Seaboard High Density Polyethylene Sheet, Matte Finish, 1/2"

Then:
First I made reinforcement templates out of craft paper sized to fit inside the storage opening and transferred them to the plastic sheet. I cut the sheet with a table saw and radial arm saw and chamfered the facing edges w/ 1/4" router bit (I think I'd use a 1/2 bit if I did it again). Then I pre-drilled holes at about every 2" and countersunk the holes. Polyethylene is very easy to work with and cuts and drills nicely though it makes a giant mess of non-organic "sawdust" that gets everywhere.
I then taped the reinforcement plates to the seat-bottom and pre-drilled pilot holes. I'm not certain you need to do this, but I didn't want any cracking, particularly near the existing cracks. After that I used a torch to surface condition the polyethylene sheet and the seat bottom (which is clearly NOT the same kind of plastic, it singed when I heated it) to ensure good adhesion.
After that it was simply a matter of glueing and screwing, making sure i got a lot of the glue deep into the cracks. One more thing I did was some of the light blue "cushion-stops" on the bottom of the cushion were loose and the threads of the screws were beginning to strip. So I used some #10 x 1 1/4" screws to replace the #8s and it tightened them right up.

The result appears to be pretty sound. The cushions themselves do feel significantly heavier than prior but there is no flex in the bottom at all now. We'll see how long it lasts and if all goes well, I may do a few of the others as precautions.

See photos for results:

Great fix!

Should also make the cushions a tad heavier - which is good - they will be less likely to fly away when cruising 60mph
Will also help a little bit with sound deadening - the rear compartments.

In my old 190 I padded these rear cushions heavily and it helped quiet the boat.

—

 

[Joshua Miller]

Looks great! This needs to be a winter project of mine. Question: where did you get the Seaboard High Density Polyethylene Sheet?

 

[Leadfooty]

I bought it thru Amazon of course. I ended up buying the unbranded stuff but it worked fine. Since the post I realized I needed to trim the supports in order to get them to fit (so don't follow my photos). I tried pulling off the supports and found that the glue bond is extremely strong, wouldn't budge a bit. I ended up trimming it with a rototool, which worked perfectly.

 

[piney1]

I bought the thicker board off of eBay, there is the seller in Fort Lauderdale that will cut you the exact size piece you need. I’ve had to replace two so far - I just replace them with the thicker board but the branded stuff.

 

[twentiesforever]

Where can I find some of those cushion stops? I cracked a few of mine and dont see them in the parts catalog. Ideas?