Re: Help for Plank attachment plates for the hull & plank

[thistle3966]

Hello,

I don't mean to interrupt on this thread, but it somewhat pertains to my current project.

I have an older hull that I am updating with some newer hardware. I have started to locate the plank plates onto the hull (Sarnes Alternate Attachment Plates). I was wondering if the max/min dimensions of F-1 (103/97) are on center measurements? I assume they are based on the schematics of the sheet 2 top view, but wanted to clarify before drilling holes.

Also, what is the recommended practice for the 5/8" holes through the cockpit flooring? Do I drill through the entire thickness or just enough to counter sink the nut?

Thanks in advance.

Craig K
5484

[Geoff Sobering]

   There is no restriction on how far apart the plates can be...

In fact, there is no requirements to use the plank-mounting hardware shown in the plans. I have seen a number of systems that don't use anything like the studs and plates.

Cheers,

Geoff S.

[Geoff Sobering]

I can't understand that part (block capitals):
I.15.b) the runner plank mounting system shall be located
in area does not exceed 30" IN THE FORE AND AFT DIMENSION.

IIRC, that restriction was put in place to prevent someone from building a "plank mount plate" out of Carbon or some other exotic material that significantly stiffened the bottom of the boat (ex. from the bow to the stern).

should I have oval holes in both plates (both side or just one side like it's shown on picture)?

Ovals in one side only.
Also, remember that the stud moves inboard as the plank flexes, so you want to leave room on that side of the oval.

Cheers,

Geoff S.

[DN 805]

To make sure you are complying with the spec. F-1 maximum and minimum dimensions I suggest that when you are installing your plank mounting hardware that you consider using the following procedure to "triangulate" the plank to the fuselage to make sure the plank is centered and the ends are equal distance from the pivot of the steering runner:
1. Hull bottom-side-up.
2. Mark centerline of hull by pulling taught a string from the pivot of the steering runner to the center of the tail of the hull.  
3. Place mark on the bottom side of the runner plank.  This mark should be equal distance from the center of the side chocks and on a line between the pivot bolts of the side runner.
4. Place the runner plank bottom-up on the hull with the center mark aligned with the center line of the hull and also positioned fore and aft within the maximum and minium dimensions in F-1.
5. Measure from the pivot of the steering runner to the pivot of the side runners, making sure the measurement is the same port and starboard.    Now your plank and hull are "triangulated".
6. The above procedure will identify the position of the plank mounting hardware.
7. Make sure, however, that there is solid wood between the floor and the bottom.  Use screws and do not glue them in place. In case of an accident, this will allow the runner plank to tear away from the hull with minimal damage to the hull and runner plank.    

[Geoff Sobering]

what is the recommended practice for the 5/8" holes through the cockpit flooring? Do I drill through the entire thickness or just enough to counter sink the nut?

I would drill all the way through.
That way if the plank pulls off the hull it will just rip the plate off.
If you had some hull structure between the nut and plank, then you would probably have (much) more hull damage.

I also use a 3/4" hole to give some space for the socket.

[Paul Goodwin - US 46]

I go even farther than Geoff,  I drill 1" through holes.  That way there is no problem getting the socket in the hole, even when you make sloppy off-center holes like me.

-paul

[Geoff Sobering]

I go even farther than Geoff,  I drill 1" through holes.

Now that you mention it, I think my drill-bit is 1".

... even when you make sloppy off-center holes like me.

And me!