Peter wrote:
That one may have dug into the sand in the shallow water.
Probably not true, and irrelevant. The canopy will slam closed, as has been documented in other cases.
Jettisoning the canopy has its own risks. To start with, not all of them are jettisonable. Then, the departing frame and canopy bubble might well hit the tail, which could have dire consequences…
Believe me, over the years we (many threads on VAF, talks with military and S&R pilots, talks with ferry pilots and others having done a couple of long overwater flights, earthrounders and others) did a lot of brainstorming on Van’s RV method of ditching, and surviving. And I tried to adapt my equipment, and mindset, for a ditching…
That one may have dug into the sand in the shallow water.
Obviously I’ve never tried this but you will struggle to smash plexiglass. It is really tough. You might just make a hole and it will help water to get in.
Based on the little I know I would jettison the canopy before ditching, and make sure the harness is tight.
Graham wrote:
Is there anything to be said for sliding the canopy back before ditching?
An absolute no go! Have a look for instance here:
The canopy will slam shut violently.
Item 19 of my checklist contains CANOPY LOCK ………………… UNLOCK & BEND
The reason behind it is to have the canopy unlocked, but not open. As to bending the locking hook down is to prevent an eventual blocking of the forward part of the canopy.
Is there anything to be said for sliding the canopy back before ditching?
I’m flying an RV-8 at present and I always carry a tool for smashing the canopy in case we end up upside down, but that’s on land.
Honestly I would not try any special technique other than a normal landing attempt when ditching. It’s already going to be high stress, and we don’t tend to fly terribly well when everything’s going wrong, so doing the kind of landing you’ve done thousands of times before seems the best way to have a successful outcome.
Ok, back on line, with hopefully some relevant info re your query/concern…
Case #1, the most documented case of an RV-7 ditching after a disastrous mid-air collision on the eastern coast of the Adriatic. There are still plenty of live vids of the event, anyone interested please use your search tool (try Adriatic Coast Italian Airshow Crash). As for the surviving pilot, he made a pretty detailed account after the event.
Looking at vids, one can observe a near perfect touchdown with that -7, tailwheel touches first, and then the RV flips. Why? I played that vid quite a few times back and forth, and came to the conclusion that the speed was too high. One cannot say for sure, but a slower and more precise speed control might (sorry Luigi, I sure would have not done any better…) have prevented the RV from eventually flipping.
Plenty of other documented cases of RV ditching. Nosedraggers vs taildraggers, basically no difference on the outcome, most of them flip (or splat). The nose dragger ones, even on a good ditching touching main wheel first, end up digging the nose, the nose gear is ripped off or bends, and then the “vertical cartwheel” happens. For the tailwheelers, no big difference, the main gear digs in, and the airframe makes a nice arc and splashes down inverted. Experience has proved that those inverted RVs sink within 3 minutes… and that is the time you have to extract yourself from the inverted (or upright) craft, gather all of your survival equipment, and then try to survive more. Coincidentally we had some good talk on the subject last nite at Popham with an RAF guy who will set for a circumnavigation on his RV-7 soon, Hermann who with his RV-8 now completed his 4th NA crossing, and myself. The RAF guy will be flying with a combined parachute/raft attached to his back, so no ditching is the plan for him. I was not aware of such a system, but contemplated wearing a chute, but then decided on triple checking that my engine would keep producing power instead 
VAF produced at lot of chatter as to best technique to prevent the aircraft to flip, but no solid conclusion. Some people preaching stalling before the actual splash, others talking about digging a wing in first…
The last 2 pages of my Blook mention some of the thinking I had whilst preparing for the Tour.
Case #2
I’ve made a couple of presentations of the Tour, and I quickly talk about this one:
Van’s RV-6A, N776WH
That is the case I modelled my checklist on. Zero flaps does not, on the plain flaps equipped -3, -4, -6 (including the -6.9i), -7, and -8, significantly increase the stall speed. But the splash down attitude might be higher and therefore prevent a flip.
Anyone out there, with an RV, to demonstrate the theory?
PS
Since I have a slider canopy I installed quick release pins, carried a multi-saw + an emergency scuba dive bottle + a survival axe, all in addition to the raft and survival suit, etc. Maybe that would have helped my egress in the icy waters, maybe not…
It will be equalising on the way down to the bottom, and will fully equalise on the bottom; that’s for sure 
But nobody will be getting out after the moment the sinking commences.
Peter wrote:
I would bet the crush depth of a “submarine” made of 3mm plexiglass is less than 10m, which will be reached in a few seconds.
Surely as it’s not a sealed cabin, the pressure will be equal inside and out so no crush effect as it sinks.
Peter wrote:
all buyoancy will be gone
You have some buyoancy in wings and fuel tanks.
The clear indication is in case that all is gone is remain air gap only on the rear side of cockpit,
the heavy engine goes down first…
In case the plane cockpit is already under water pressure, wait to fill up to the top, hold your breath or use spare air
The problem with waiting for that is that by the time it fills up, all buyoancy will be gone and it will be sinking at a great speed and nobody will be getting out. I would bet the crush depth of a “submarine” made of 3mm plexiglass is less than 10m, which will be reached in a few seconds. So you have to get out immediately.
hold onto a known location with one hand. During the egress hold onto successive known locations and never let go with both hands
I believe that is from a standard helicopter ditching course. These can end up upside down but won’t sink further because the floats will stop that. You “just” need to somehow get out of there and get to the surface. An RV is nothing like a helicopter.
