what type of foam is used in the seats and what thickness if anyone knows

im thinking high density foam and 4in thickness?

i have some frames i built a few years back that i need to finish up.

its side seats and buckets i suppose

going into an 18footer

and wheres a good place to pick up some vinyl and piping

I used a combo of both blue and yellow and they come in different sizes. The blue is soft and yellow firm. The yellow will cost you more. I used blue on sides and head rest and the yellow for seats. 3" is plenty and you can even use a 2" yellow and a 1" blue glued together to save cost. I also used white 3/8 marine foam under my carpet as well my hatch cover. I bought all my vinyl, carpet, piping...ect from UFO in san deigo.

so i got 7.5 yards of 3" high density foam, 7.5 yards of white vinyl (its all they had in stock) and 1.5 yards of blue for the piping. My girlfriend has some piping cord that im going to use to make the piping. plan is to make them white, with a 2" blue stripe down the middle of the seats, and blue piping as well.

going to SLOWLY start making a pattern for it, as im not doing the same as the seats are now. should be fun.

Thats how I did mine....1/8 on inside borders and 3/8 on outside borders...

You talking about the piping sizes right?

What about where the seat meets the inside of the hull?