Hello everyone,
regarding the use of the Merlin as a SAR platform, we at the Portuguese Air Force are doing just that. May I remind you that we upgraded from the Puma S1 (Makila 1A1 engines), which unfortunately we didn't sell to the RAF.
Regarding the use of the Merlin as a long distance platform, I have no way to compare it to the S-92, although some of our guys who were at the replacement programme from the start said the cargo door on the S92 was very small, and you'd get problems when working with stretchers.
One big disadvantage over our Puma is the position of the winch, way back in the helicopter, which means the pilot has to be too forward of references when working over small vessels, etc. The Danish have a better position for their winch (almost behing the pilot), and a cargo door on the port side of the helicopter, which can also be useful.
Regarding the downwash, it is true that for cliff rescues it can be dangerous, however, regarding small ships we haven't had problems. Our Sar Techs spent hours in the water testing different hover heights, did hundreds of winching ops, and we came to 60ft as the ideal height for winching, which ensures that the Sar Tech will be out of the downwash on the descent and in the water.
Regarding small ships, if they can maintain a course and speed, we'l direct them to wind 30 degress port side, and the added ship speed and wind speed will usually mean the downwash is way behind the a/c. We haven't had any problems when we stick to this procedure, however if you try it with a tailwind, you'll get into trouble. We train at night with a 40 ft navy patrol, and the downwash of the helicopter, in tailwind conditions, has made the ship turn 180 degress!
If the small vessels can't maintain a course and speed (adrift or sinking), we usually pick the survivors from the water or from their liferaft (we tell them to tie a rope to the ship and put themselves in the liferaft). If there is someone really hurt and unable to exit an adrift vessel, then we have to use hi-line and we can't choose where the wind is blowing from if they can't manoeveur, and that's the only situation where downwash will really make a difference. Two days ago I was winching 3 frenchmen from a liferaft close to a drifting trimaran (45 ft long), and we almost turned the trimaran on its head...
Regarding hover references, well, with auto hover you don't need that, unless you are over bigger ships, where you do visual hover, but then you have the speed advantage, and downwash is not a big problem (hasn't been for us). I know the Canadians have been through the same problems as we have and have come to similar conclusions. It's a good a/c, but maybe not the ideal for cliff rescues or small vessels, however, I wouldn't go back to the Puma, doing rescues at night from 30 ft fishing vessels, without NVG's or auto-hover
.
Cheers
Pinho