1990 26' Sun Dance CC rebuild

[Total Chaos]

I feel like a deer in headlights.
Here's a little history. I hit something in the gulf a few years back(turtle I believe), it developed a crack alongside the chine in bow area. I cut the hull open in that spot and found it to be an open space inside, under the stringer, I dried it the best I could and then pumped it full of West epoxy/filler(hull thickness is solid 3/8"). The next year the crack came back so I took it to a professional boat repair co. in Pensacola. They took out the inner front fish box, it opened up the entire inside of the hull between the stringers up to the bow. They ground and layed glass/polyester resin(built it up about 3/8").
The next year I got the $##@*&# termites. Did the rip down to find the stringers were indeed delaminated and wet/rotted and not completlely bedded to the hull in alot of places(I don't get it, some boat builders let this sort of thing happen). I would imagine there was some flexing going on for years.
I've had spider cracks in that area before, but I haven't noticed the lateral cracks before I started the rip down. As for the dirt in the cracks, I probably wiped the dirt into the cracks.
I will take all of your advice and do some grinding and inspection. I've done alot of work on the boat allready, this shouldn't stop me.
Stay tunned.

[FitzFisher]

I was just reading Larry's link to the survey discussion and then went back to look at your earlier pictures. It looks like they only built two sets of frames in the area outside the stringers and that a very long section in the middle had no frame. Based on the length and nature of the cracks, it appears that they are in an area that had no frame support, which allowed the panel to flex too much. So then as long as the glass is still structurally sound, you may just need to add another set of frames or so in the area where the cracks are to fix this design issue. I lean toward the idea that frames are generally under built, but then I don't build race boats. I like the idea of a solid framework under my sole when I'm pounding through 6 footers trying to outrun a storm (see my setup on the 21 footer I am rebuilding).


Some may feel this is overkill. the distance between frames is ~3ft, with 28-21 inches between stringer and chine. The original builder only used two sets of frames, but does layup a lot of glass in the hull to reduce flex. I went with three for the extra hull suppport and the fact that I can now use something lighter than 3/4 marine ply for the sole. Just an Idea...

[Guest]

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You guys were correct. There are cracks that penatrate under the gelcoat. They appear to stop about 1/16 to 1/8" into glass, at least on what I ground out(noted on pic). The entire area that has these cracks is limited to about a 4 ft. section in length(bow to stern) and 16" up each side measuring from the the centerline of hull.
Approx. area on inside is noted on other pic(this was taken after the demo, did not have a up to date pic of this area). This is the area where boat repair shop built up on inside between stringers prior to rip down, they also did some grinding on outside that covers a small section of the effected area and applied glass/resin.
What do ya think?

[Total Chaos]

Thanks for the link CL, it was very informative.
Fitz, you are right, there does not appear to be enough framework to support that area where the cracks formed and also where the original cracks were found after hitting something. That area acted like a hinge when it flexed. I should be able to add more framework but will only be able to do it between the stringers since the deck is allready installed. I won't do anything until I get some feedback on the hull condition.

I did some grinding today to find out the cracks went into the laminate, but doesn't appear deep(1/16 - 1/8"). Today, I loaded a previous post w/ pics and explanations but for some reason a message came up saying "the moderator must review before posting". I will wait till Sunday and if not posted I will post it again.

Thanks all.

[TomW]

If the cracks were 1/8" into the bottom layup they were at least 1/4 - 1/3 into the total fiberglass of the bottom of that boat. That's not good. Because while the visible crack is that deep the rest of the crack exstends upwards through the rest of the lamination.

[Cracker Larry]

I agree with Tom, the damage is much more extensive than you can see. There are fractures all through the lamination. That's why I suggested a surveyor.

[Total Chaos]

Here are the pics

[shine]

I am sorry to see the cracks going through the laminate. The fix is not easy, you will need to lay new glass on the inside of the hull. A patch on the outside will be just that, a patch.

There are dyes you can use that will show how far the crack go. I will look for a source for this when I get into the office. Basically the dye is sponged on and it creeps into every crack, so as you grinding you can follow to see how far the cracks go

[Total Chaos]

I'm back, it's been awhile.Here's what I did to finish the project. I was so busy trying to get it done, I did not stop to take any pics of the progress, sorry.

I found out the outer hull skin was made up with a layer of chopped glass and resin directly on the gelcoat, then several layers of hand layed glass. The cracks went as far as the chopped glass then stopped. I ground the entire area and put 2 layers of 1708 w/ Marinepoxy, then faired and repainted Awlgrip.
On the inside, this area was built up before from a previous fix from a repair shop. I put another 2 layers of 1708 and reinforced between the stringers to the hull w/ 3/4" Meranti, bedded, tabbed and glassed in in 4 places.

I launced her in April last year(see pic). Due to the bracket being added, I was really concerned as too how she was going to sit in water. I am pleased.
Initial shake down cruise resulted in 4 MPH faster at 4000 RPM's(39/40 mph). Ran smooth and straight with no listing to either side. What I was really pleased with was I could stay on plane at 2800 RPM's w/ 4 people, gear, etc. and before I couldn't drop the RPM's less then 3700 before it came off plane.
I did have to notch the motor mount part of the bracket to get the motors lower due to slipping of the props. It was easier to notch it then drop the entire bracket down on the transom.

I've been able to cruise 30 mph in 3 to 4's w/ a pretty comfortable solid dry ride(as what a center console would give).
Oh, the livewell works like a champ. I'll post some pics to show what I did.