1981 Chaparral 198 Bowrider Stringer/Transom/Floor Replacement (*Long*)

[Geoffman72]

Hi everyone,

Nice to finally find a site with good information! As I said in the title, I've got a 1981 Chaparral 198 Bowrider that I pretty much had handed down from my parents as they let it sit out uncovered and well, you know.
The factory 3.8L GM 229cid V6 died a few years back thanks to the oil pump pickup tube falling off (was a replacement engine and some idiot really did a half assed job) so its been slowly rebuilt and was finally ready to go back in about a month ago.

I've progressively realized over the past month just how bad a shape this boat had gotten into. Chalky gelcoat, interior cracked shot and half missing, plus a few soft spots in the floor and a ghetto transom patch job.
I started pulling up the floor hoping for a simple floor replacement.
Nope.
I'll get to the point by saying I found the wood for the transom behind the ghetto patch job and the stringers could have been mistaken for chunky butter past its expiration date.

Before I get into questions, I want to state the goal and intended use of this project is to get the floor and structure of this boat completely replaced and sealed so this boat will last a good while longer as it does have sentimental value. Otherwise I'd probably end up buying a friends 22' Sea Ray Pachanga with a 450hp 454. :o
As for what stress its going to see. At worst its going to be used on Lake Ontario doubtfully ever going out of sight of shore. I doubt id ever take it out if it wasn't gorgeous weather, though some of the local yachts put out quite the wake.

Heres the questions that I have;

1) I'm on the fence about sea-cast, both for the transom and stringers. I'm leaning more towards good old traditional get it done right wood though. If anyone wants to help provide further cause not to go that route, by all means.
2) I've read for setting the stringers, assuming wood is used, they should be held about 1/4" off the hull with foam or the like. Are they just glassed to the new transom afterwards? (probably have that question answered myself once I hack that far back on the boat.)
3) For strength when setting the floor, I'm planning on doing a 70 degree scarf joint using the remaining outer 3" of old floor where it was glassed to the sides at the factory. I''ll be using epoxy through this, but I'm a little unclear as how to mate the floor to all its joints to seal it up.
4) I'm hoping to get away with leaving the gas tank and its full 25 gallons of fuel in the boat as well as the hatch for storing gear. Should there be any foam or anything that could warrant taking the tank out?
5) I should probably also state im doing all this on the back of the trailer. The Chaparral is a pretty sturdily built boat, but should I be concerned about the hull flexing while doing all this work?


I'm sure I'm forgetting a few questions, but its late and this is a pretty long post already.
Here are some recent pictures of the project, and thanks in advance for any help any of you can provide!

http://www.filechamber.com/viewalbum.do?album_id=1269

[Geoffman72]

Anyone?

[marshmat]

Hi Geoffman,
Welcome aboard. The forum has an internal search engine and a lot of old threads on similar subjects, so try that.
As for your questions:
1) When doing repairs, always do them right. Miracle goops, etc. may work in the short term but if you want something to last, do it right the first time. In a fibreglass boat that means using high quality resins, prepping all surfaces properly, and in many cases avoiding wood in favour of more rot-resistant materials.
2) We see a lot of complaints on this forum about rotted wood stringers; have you considered spending a few extra dollars for marine-grade foam? As for laminates, when you cut away the rot you will see how many layers of glass are on what areas of the boat; this isn't necessarily how many should be there. High stress areas like the joint between stringer and transom need extra care and more glass. Just about everything in a fibreglass hull is held together by these laminates, so it's worth doing some practice samples to get used to using the materials.
3) If this is your plan, the only thing I can think of is a lot of cut, test-fit, cut, test-fit, etc... and then use a filled epoxy in the scarf; glass overtop.
4) The tank should not be foamed in, it should be securely strapped in and not be touching the bottom of the hull. If it's foamed in, and is made of metal, it's probably corroding underneath. Use extreme caution in the bilge if there is fuel in the tank as either the tank or its fittings could be corroding or leaky. I would probably siphon the gas out and purge the tank before doing any work down there.
5) If the trailer has four large, solid bunks that touch the hull evenly, you're probably fine. If it's a roller trailer, or if the bunks are small, I would prop the hull against the trailer frame using 2x6s as bunks, before you start cutting stringers. You don't want the hull to warp at all, and it won't hurt to be cautious here.

[Geoffman72]

Thanks for the help Marshmat!

I've been studying the older topics since I found the site pretty relentlessly. I've pretty much decided to go with wood for the stringers and transom though contouring them to evenly flow 1/4" above the hull is going to be quite the chore.

I'll definitely be spending the extra dollars for the appropriate materials. The underside of the floor was not coated from the factory and I doubt the expanding foam they used in 1981 was that great.

The floor is at least whole so I'll be trying to remove it in large pieces and hope to use the pieces as templates to hopefully get me right in the ballpark. I'm currently deciding whether I should do a 45 degree cut which my saw is capable of or buying the scarf joint attachment from west marine.

As for the gas tank, we'll have to see. I still have yet to do much in that area but its probably a good idea to get that old fuel out for both safety and for the new engine when it finally gets to its new home.

The trailer is a roller unfortunately. My thought is that as the current stringers are only supporting anything with the fiberglass encasing, I was planning on cutting the top off the fiberglass, scooping the old wood out plus taking care to make sure every last nuance of it is gone, then sand the fiberglass down and coat the sides of the new stringer board to adhere to the old glass.
This does seem a bit taking the easy way though. I'm worried about completely stripping it and things not lining up as well as they should with the new material. Suppose I'll just have to be really particular about measurements!

Thanks again for the help, and for any future help you or anyone here can provide!

[marshmat]

By all means, keep us posted on your progress! :)

[jimslade]

My response would be to long to post. If you want to call me, I live just outside of toronto canada. I just finished the same project your into. I could give you detailed advice. I wouldn't want you to waste your time or money. I have extensive experiance with glass. My business is autobody repair and my hobby is Boats. My Phone # is 905-640-1123 Jim Slade