CS17 #339 Help on centerboard case

[acreew]

Centerboard case has been a challenge. Have it in place but have several questions;

1. used 3/8 ply (do over and did not have more 1/4 ply)....is this a problem

2. top of case on 1 side is about 1/8 inch below seat tops...is this a problem

3. having hard time visualizing the cap....where does it go.....does it add height to the case?

4. did not mark pivot hole location before fitting the sides....how to find the correct placement for the pivot hole?

5. Should I just start over....and if so would someone share the most efficient way to go about it?

 

Attached are a few pictures of the build and  2 of the case as it is now.

Appreciate any help. Thank you.

Will

[LennieG]

Acre-

I'll let the experts weigh in mostly, and I am away from the plans, but I think what matters as far as height is top of the seats matching up with top of the cap. Your description doesn't sound problematic. What matters as far as the width is the internal diameter vs your CB and I think the difference should be 3/16th. I wouldn't think the 3/8 " ply matters. I think also the glass on inside of trunk matters and I don't see any on yours. I would think the plans point to the location of pivot hole. You might need a right angle drill attachment.

The boat looks good. Good luck

[mattp]

I am still in progress with this boat and am certainly not an expert but I'll give it a shot:

1) I can't see why this would be a problem. It would put your cb further off center by 1/8.

2) top of trunk frame should be on same plane as bottom of seats. Forward seats will attach to trunk.

3) I haven't gotten there yet but I think the cap attaches to top of the trunk flush with the seats

4) I marked my pivot from the plans and double checked clearance with cb

5) Hard to tell. Seems like your biggest problem is the frame not lining up with the seat tops but I wonder if you can have the problem side float above the bottom and filled with thickened epoxy.

[PAR]

With the deadrise in this area, drilling for the pivot bolt (after installation) will require an 90 degree angle attachment on a drill.

[Designer]

You have been given good advise. The extra thickness of the trunk won't hurt you. The top of the trunk cap needs to be flush with the top of the seats which are flush with the top of the side seats.

 

It is best to build the centerboard and trunk together so that you can see that the board can rotate properly without fouling and drill the pivot hole more accurately. You are beyond that point now. I would lay the board on top of the keel batten next to the trunk so that you can check the right fore and aft position. Poke a pencil through the pivot hole in the board and mark the trunk. This will give you the fore and aft position of the hole and it will be 3/4" too high. Just drill the hole down 3/4" below the mark. While we like to drill the hole perfectly square, remember that the board only rotates through about 90 degrees, if you are a bit out of square it will still work.

 

Remember to make a good seal between the middle seat and the trunk as well as the cap. The water slams back up in there and it will leak if it is not well sealed. 

[acreew]

Thank you all very much for the helpful and prompt replies. I was not clear in the original post.....I have not epoxied the case in place yet and can take it out and adjust it. Don't know if this would change your recommendation Grahm for locating the pivot point. The measurements for the pivot hole appear to be from the bottom of the pre-cut ply.......I am guessing that I can just make the measurements from the bottom of the shaped case with a little donward adjustment on the height measurement?

 

Will get the 90 degree angle attachment.

 

I plan on glassing the inside of the case....just afraid of making some big mistake with dimensions that will interfere with subsequent steps.

 

I will also double check the clearance of the CB, best I can tell I have about 2/16 clearance.

 

Not sure I understand floating the shorter side above the bottom. Is it also possible to adjust the height (slightly) by adjusting the rails....that is making the rails flush with the seat tops even if they rise above the case sides by 1/8 inch or so? Also, if I am understanding.....the cap will also increase the height of the case by 1/4 inch?

 

Thank you all again for the very helpful advice.

Will

[PAR]

If you case is removable, you don't need the 90 degree drill attachment.

[acreew]

Thanks PAR.....initially thought you were referring to a guide to ensure level drilling....understood once I saw it.

[LennieG]

The plans say that if you have less than 3/16" clearance the CB will jam. Sounds like you need to rip new king posts.

[Dnjost]

If you have not glassed the CB case yet, you could add fiberglass shims to the king posts then reassemble the sides.  Or, cut new king posts (probably would be quicker).  

 

I did a mock up of the cb side panels using Masonite, and scribed the bottoms to fit the hull.  This worked great.  

 

I hope to be doing a similar installation this weekend (if weather allows) and will post photos if this comes to fruition.    

 

It would think it would be much easier to fit the CB and pivot with the case out of the boat. I have the pivot point marked on the board, and will fit it to each side prior to final glue up and assembly.  

[MisterMoon]

After the Everglades Challenge and 302 nautical miles of centerboard slot spitting water into the off-watch crew's rear end and the lever on the top of the board hitting them in the crotch every time we touched bottom, I'm seriously considering putting in a weighted board and sealing up the top of the case. Something to consider...

[acreew]

Agreed... Will rip the new posts, fit cb, and test clearance.

Weighted cb and sealed case sounds interesting....how would you go about it?

Look forward to the pictures Dnjost... I will be a while before messing with the case again...once bitten twice shy

[acreew]

Holy moly.... Just looked at your blog Dnjost... Provides excellent guide to fitting cb case.... Thank you.... Will be starting over with greater hope of success...won't tell how I attempted but probably walked 5 miles between boat and workbench....this stuff doesn't come easy for me.... Thanks again

[Dnjost]

Acreew - 

did a little more today...The board pivot is in, and the board tested for placement, and further shaping if necessary.  The one thing I am glad I did was mark the pivot point on the plywood prior to cutting out.  Things are going well with this approach.  Will glass the interior of the trunk over the next several days, finish the shaping and fairing, then glass the blade. I am fortunate to have surplus bronze rod hanging around that my grandfather used to use for garden stakes in a garden that was frequently flooded by saltwater.  

 

Photos are up. Now that I know someone is looking, will be more careful in what i put up in print! 

[acreew]

Hey David. My name is Will. Thanks for the update. I will check it out and am very glad to have found your blog....keep it coming. Yup...I will start over and do it the right way. The build has gone beatifully to this point....no sense in taking a risk with the placement of the pivot. Thanks again.

[Phil Garland]

Mistermoon,  we eliminated the sloshing water in the CB trunk by putting a product called Slot Strip (available at APS) on the bottom of the trunk opening.  It is flexible yet stiff centerboard gasket material that is dacron cloth with mylar on one side.  The dacron side is glued down with Sikaflex.  The two strips on either side of the trunk overlap about 3mm in the center.  At the front end of the trunk I have a layer of fiberglass and epoxy to protect the front from peeling away.  It almost totally eliminates the noise and water sloshing in and out of the trunk...dramatic difference.  It has survived the beach launchings of the EC and with the trunk off-center it is pretty well protected on and off the trailer.  Not to mention it also eliminates a lot of drag.