Stringer question...85 Checkmate ski boat

[emilime75]

I am looking at an 85 Checkmate ski boat as a project and had a question regarding the stringers. I know one of them has rot and the other seems OK, at least it does where I can get a look at it without ripping up the floor, but I will assume it is bad as well. The floor is a bit soft on the rotted side, but seems solid over the stringer that appears to be good. This is an outboard motor so they are not used for motor mounting.

My questions...

How important are the stringers to a boat's strength? Will it break if I used the boat till the end of the summer with the bad stringers? Or are they there primarily to hold up the floor? Please excuse me if this seems like a stupid question, I am just very, very, very new to boats and know very little about them.

 

[NoKlu]

Re: Stringer question...85 Checkmate ski boat

To put it simply,the stringers are the frame of the boat. If the stringers are gone the hull has nothing to support it and will twist and move as the boat hits waves. This can result in a complete hull failure and a trip to the bottom of the water body you are currently on. The transom your outboard hangs on is part of the frame. The motor pushes on the transom which in turn pushes on the stringers so if everything is rotten you can see how bad things can get in a hurry. If one stringer is soft you can be assured the other is bad as well and the transom is probably in the same condition. Do a search on core samples and read the completed boats forum to get an idea of what you will be looking at to repair the boat your looking at.

 

[NSBCraig]

Re: Stringer question...85 Checkmate ski boat

First what model do you have?

Checkmates are fully balsa cored and as such hold there shape without the stringers unlike conventional boats.

if the one side is bad it's most likely from someone's stupid repair or add on, so it doesn't really mean that all is bad.

Post some pics let's see what we're dealing with.

 

[NoKlu]

Re: Stringer question...85 Checkmate ski boat

Can you explain the Balsa core thing please?

 

[NSBCraig]

Re: Stringer question...85 Checkmate ski boat

Sure after they spray gel coat in the mold, they had lay glass cloth and mat, they put end grain balsa core material in.

In Checkmates case the entire hull is done, my Baja only has the bottom out to the chines not the sides. Then they lay more glass inside and vacuum bag it.

Checkmates are very high quality boats

http://www.checkmatepowerboats.net/manufacturing.html

The attached pic shows a checkmate with core, inside glass and stringers installed.

But if you look at it you'll notice that the stingers system is really a ski locker and bulkheads to hold the floor up more than stringers for structure.

Again though it really depends on what model we're talking about and size.

Any help?