strake repair help needed

[Blizz]

see if these are a little bigger so you can see.

 

[Blizz]

In the top pic you can see the fracture right in the middle then if you look around the edges of the wear marks you'll see where the glass stops and the putty begins on all of them.

 

[wickedrister]

Good Thread

I'm not far from flipping over my project boat and start working on the bottom side. Have a few strikes that are chipped and a few blisters that need looked at.

 

[Eaglenva]

Eaglenva, What motor will you be using? Have you considered modifying the hull like adding a pad?

it came with a 1974 Johnson 70 hp, fired right up but smoked bad and did not "sound right", so i will be taking it to a local mechanic to look it over. probably replace it when i have the $$. keeping an eye out for the max hp, label says 140 and the brochure says 150 and that was before when they measured at the crank instead of prop. so that said, looking for a post mid 80's 140 when the time comes.

as to a pad... HUH? not sure what one looks like, thought perhaps the flat spot on the bottom was a pad. DUH, guess not - LOL. its about as wide as a ski.



now as to all the other discussion (which I REALLY appreciate)...
on the strake/chine? it is completely through the outside layer of glass into the bondo stuff inside but not thru to the core or interior glass. I would rather not cut the inside if possible but will if necessary- especilly the center cracks!!! that scares the crap out of me!! what i would prefer is - the strake area is like a straw that has a hole in the middle of it. i would like to dig out the area inside the "straw" back as far as possible may 1/2 inch to 1 inch on each side, then fill with solid fiberglass and resin (or something similarly solid) and shape to match the original area.

as to the bottom center it looks rough. I had hoped to go over that with a layer of mat glass on the outside from one strake to the other covering the entire area and the feather it into the original glass. this would be a minimum of 4 feet long and up to 6 feet if I take it the entire length of the first strakes on each side. the inside core is not discolorrd and it sounds solid. it does look like some crack in the glass though and some of the dark paint is still not off the glass yet. need to finish sanding to make sure that area is not under the glass.

 

[Blizz]

I myself would not repair this way, i understand you want to doit the easiest way but unfortunatly it's not always the best or safest method. And with all the other hull imperfections you may be surprised with what you find under the floor (wet foam, rotton stringers etc). With the 140 you'll be able to see speeds well into the 60's when you get it setup properly and trust me you donot want the boat to delaminate at that speed it's not pretty. If you want to try something kinda elementry but will kinda show you what i'm talking about. Take a piece of cardboard and bend it in the shape of the strake then try to bend it it should be fairly strong now cut out a piece matching on of your missing segments it's now extremely weak know tape the piece back in should still be fairly weak know take another piece of cardboard abit longer than your cutout and tape it to the inside of the original it should be pretty strong. sorry for being long winded. And oh yeah there is no real strength to your repair if you only use mat. I just want your boat to be safe when your done with it so you can enjoy it for years to come.

 

[Blizz]

And don't let cutting the floor out scare you it's easier than you think as long as you take your time. a floor can be done in a couple of days.

 

[Blizz]

Wicked if your hull is just chipped and blisters these are easy fixes as they are not structural.

 

[Boston Predictor]

Blizz, I understand exactally what you mean, but we're not talking about tape and a single peice (strake) of cardboard.

The strake is already connected to the hull, and has plenty of strength there. When its filled, FIBERGLASSED, and gelcoated properly, Delamination should not be an issue...

 

[Boston Predictor]

BTW FYI he already tore up the floor and transom

 

[Eaglenva]

Safety is the primary concern... that comes before looks, ease, anything. I knew they did that to metal to strenghten it, I thought the strakes were just to help lift the boat out of the water, not strenghten it. I know there is a lot of kenetic energy during that impact.

yeah, its gutted. nothing but a hull right now with no transom so i can easily get to what i need to. i understand its easy to cut a hole through the hull, its keeping the water out later im worried about - LOL - you know, filling in the hole.

so Blizz is suggesting i remove the internal core matting in a section apx 22" X 48" to repair them. the reason i clarify this is by going 2" beyond current damage gets you into the next area of damage. what if i added a bulkhead inside to reinforce it? again I want it safe first and what I feel is within my capabilities second.

BP you feel it would be solid enough if I dig in to the core (not through the hull) and fill it like a tooth with pure glass.

to see all the pics the link is in the signature below. The transom is further along than the pics, I have removed all the bondo stuff from the transom so it is just glass right now.

 

[Blizz]

Ok if you don't want to cut out the core you can fix from the outsidebut it will not be as strong and there will be alot of sanding and fairing to do. A standard repair where the glass is completely gone is to fiar out approx 1/2 inch for every layer of glass in the layup so if your damage is say 2"x6" and your layup is 5layers your repair would have to be atleast 7"x11". For what Boston said above the strake is not connected to the hull, it is the hull and it's comprimised. Even if you just fill them with glass you will need atleast a minimum of 2-3 layers of woven or bi-axial not mat on the outside (again mat has NO strength to add to your repair that's why boats that are considered chop boats are junk and boats that are layed are good). To do the repair from the outside you will also need to remove all the gelcoat where you are doing your layup. And if you can do what your doing to the rest of the hull you can change a piece of core without getting in over your head. I've seen boat delaminate and it's not pretty i've also seen them break in half hitting a wave the wrong way atsub 50 mph speeds. However you decide to fix i will be happy to help out anyway you see fit or answer any questions i can.

 

[Blizz]

Oh and i forgot either way you fix it it will need glass on the outside.

 

[Eaglenva]

with the layers of woven glass that will create a "hump" in the strake, wont that effect the way it acts with the water-especially doing several on the same side? do I need to make both sides match? what is fiar? Thanks!!

 

[Blizz]

You need to remove some glass before you put new on fairing is just the final blending to make it smooth and pretty. If you don't put something over the outside your repair will crack around the edges the layers on the outside can be light weight if repaired well.

 

[Eaglenva]

so looking at it from the side like a cut out...


regular surface level ---___ ground down a layer or 2 but not all the way.

then fill in the low spot in a overlap format?

 

[Blizz]

Pretty much that's the idea here's a very crude sketch of it,

 

[cooperider]

The repairs for those should start from the inside if the boat, just filling those will not make that a safe repair they are well through the hull there is zero strength in those spots right now and there will be zero there if you just fill them. You need to route out the strake from inside and do a proper layup inside the hull then you can refill the inside and fair in the outside then put whatever topcoat you plan on using.Remember this is not your 35mph go to the marina boat it will take some beating when you ger her finished.

Alright Blizz, I need to step in on this thread.

DO NOT TRY TO REPAIR THESE STRAKES FROM THE INSIDE!!!!!!!!!!!!!!

On most boats you would be correct about having to fix these strakes from the inside. BUT on a Checkmate they can be fixed from the outside, heck if he wanted he could grind them flush with the rest of the hull, now let me show you why.

You see, most of the structure in a Checkmate is behind the strake. I've attached a cross section of an ACTUAL Checkmate hull.

The layers go as follows:

Gel Coat
Mat and Cloth
Then the filler for the strake.
Then mat and roving.
then another mat and roving
then mat, balsa and mat and roving.

If you look at these pics, you will see why if you try to repair this hull from the inside you will destroy the hull.

 

[cooperider]

I REPEAT, DO NOT TRY TO FIX THE STRAKES FROM THE INSIDE

Just to be clear, those pictures are an actual piece of a Checkmate hull that I cut up.


The structure is in the core, not in the strake!!! DON'T try to make this any more work than you have to.


Sorry Blizz, normally there are 100 ways to fix a boat with 95 of them being right. Fixing this boat from the inside would have been one of the 5.


Blizz, if this boat was my Dad's old Sea Sprite, or that stupid Fantasy that I had, YOU would be 100% correct.

 

[Blizz]

Cool i stand corrected on the layup schedule of the Mates learn something everyday thanks Coop.

 

[Boston Predictor]

The structure is in the core, not in the strake!!!

Thats what I was trying to say,^ and what I meant about the strake being attached to the hull, you can see in the pic. We had to repair the strakes (due to delamination at sub 50mph speeds) in my old mx-13, and we built it up and glassed in in