"M" Cockpit Lockers On An "X"??

[kmclemore]

I was reading the discussion of fuel tanks and this came to mind...
I wonder... has anyone ever tried converting the to a "lift-the-lid" type locker as on the ? Does anyone know what is under the cockpit seats? Foam? And to what width/depth can one go with such a locker? Do you think there would be more room than the existing ones? Surely it would provide easier access for stowing tanks and such.

It would seem that one could cut out the tops of the seats, lipping over about 1-1/2" to 2" onto the vertical section (where your upper calf would be when seated), then gel and glass-over the existing openings, add a 'lip' around the new opening to carry the weight of the new 'seat/lid' and then add a reinforcing member under the new seat/lid and a pair of hinges underneath at the back. My only worry would be that if there's a structural or flotation reason to keep things as they are...

Thoughts???

[Don T]

Hello:
My first reaction to this, I do not believe there would be enough structural strength left. Maybe feasible if some stiffeners were added in the process.

[Duane Dunn, Allegro]

As long as your cut in the seat is within the confines of the walls of the locker below there would be no problem. There is no foam in this area. Many have cut through the seats and put in deck plates to allow access to the top fills on the 12 gallon tanks. As I recall the seat is cored. You'd have to glass up the edges of the laminate core in the seat along the cut as well as add a lip. I could see a simple wood lip attached around all 3 sides then glass laminated over it. The liner of the locker is quite a bit thinner than the seat laminate. It might need a bit of reinforcement if it carries any of the load from the new seat lip Ideally you would want to transfer this load back into the seat structure rather than on the locker walls.

I don't see that this mod would gain much with my setup. My four tanks fill the entire locker so there isn't space for much extra. What little there is is filled with quarts of oil and stove fuel which I can access from the front. My tanks have end fills that are easy to access so I don't gain anything there. And we always have our seat cushions snapped in place which would have to be moved to open the locker.

Perhaps if you carried less fuel and had more unused space it would make sense.

[Chip Hindes]

As long as your cut in the seat is within the confines of the walls of the locker below there would be no problem. There is no foam in this area. Many have cut through the seats and put in deck plates to allow access to the top fills on the 12 gallon tanks.

There being no foam in this area does not necessarily mean "no problem." The intact seats provide considerable stiffening to that part of the cockpit. Cutting completely through the seat will reduce the seat and cockpit integrity. It does so in the M as well, but the M cockpit is considerably smaller and doesn't require as much stiffening in this area. And since it was designed to be this way, there may be other areas where the stiffening has been increased to compensate.

It's not the same as punching holes in the seat. If you keep the holes small in relation to the total area, and don't put them too close to the edges, most of the stiffening effect will be retained.

For this same reason I won't notch the inside panels for filler cap clearance any further than to the beginning of the curved part.

Want another demonstration of this principle? Unscrew the side panels on the pedestal and see how much stiffness is retained. The thing turns positively flimsy.

Might you get away with it? Certainly, but don't fool yourself into thinking it couldn't be a problem just because there's no foam there.

It's exactly the same principle as the body panels in unibody and monocoque construction in cars.

Kevin, you shouldn't need me to point this out to you. If you need a better explanation you could talk to Colin Chapman. Sorry, couldn't resist. Is he still alive?

[Moe]

I actually considered doing this. The problem with the 12 gallon tanks is that they literally fill up the compartment front to back, so if you installed blocks to support the cut-out portion from underneath, they'd block the tank from coming up vertically. They would be a nice lid to swing up to get to the filler, but I was also worried about the structural integrity, and so opted to use the deck plates.

--
Moe

[kmclemore]

Kevin, you shouldn't need me to point this out to you. If you need a better explanation you could talk to Colin Chapman. Sorry, couldn't resist. Is he still alive?

Nice cheap shot, Chip. You're right, I don't need you to point out lessons for me on glassfibre strength - I simply asked if anyone had tried this, and if anyone knew what was under the cockpit area. Obviously there would have to be some structural reinforcement when making this mod, which is why I mentioned adding a strengthening lip around the edge and one for the lid itself. I do wonder, though, how you're able to state with such certainty that "the intact seats provide considerable stiffening to that part of the cockpit"... are you privy to some of the design calculations for the Mac, or is this from your amazing personal wealth of knowledge?

And no, I can't ask Colin, Chip. Sadly, he died while I was doing consulting work for him.

[richandlori]

I can't believe my eyes....do I actually see a thread that makes it sound like a feature on an M would be desirable to add to an X? I thought compared to an M, the X was perfection....

With all the X'ers and low number of M'ers on this board....I just couldn't resist the comment, it will probably cost me though.....be kind in the responses!


Rich

[Chip Hindes]

Sorry, Kevin. I meant no offense. I thought it was humorous, obviously you don't.

[kmclemore]

Chip, I'm sure you feel your comments are witty and jocular, but sometimes they can seem to be very condescending, and it tends to make folks somewhat less than amused. And then when you combine that with snappy remarks about one of the best engineers I've ever had the pleasure to meet, who died suddenly and unexpectedly at a young age... well, I'm sorry, but yes, I will indeed find it rather difficult to find the humour. However, apologies accepted.

[Don T]

Hello:
The permanent vs removable ladder would also be an indicator of required support.

[kmclemore]

Hello:
The permanent vs removable ladder would also be an indicator of required support.

Hmm.. not sure I understand what you meant here, Don...? Are you saying that because the has a permanant ladder then the seat area is more naturally stressed? On my the permanent ladder mounts way down on the stern, just below the cockpit sole edge, so I guess I'm not sure I see how this would stress the seat area?

[Don T]

Hello:
Actually, the only M I've been on was at the boat show. It had a solid stair assembly. My boat does not have a stair, just a step. I asked them (BWY) at the time because of the "access to the rear birth" that we X owners were bemoaning at the time. They said you cannot use a swing stair there because it needed the support.

[kmclemore]

Ahhh... you meant the companionway stair/ladder/step... I was confused... thought you meant the aft (transom) ladder. My bad.