Such is the random internet surfing which has become part of my day currently  I found this whilst meandering around for RAF Jaguar information:

Masirah's airport is at the north of the island, yet there appears to be the remains of an airstrip further south.

https://www.google.com/maps/place/20%C2%B029'26.8%22N+58%C2%B047'35.0%22E/@20.5512315,58.7466375,16333m/data=!3m1!1e3!4m9!1m2!2m1!1summ+rasas+masirah+island!3m5!1s0x0:0x0!7e2!8m2!3d20.4907757!4d58.7930514?hl=en

Was this the original strip from back in the 30s when the RAF got there I wonder? Could this article refer to it? http://ukmamsoba.org/raf on masirah.htm

Quote

In 1933 Wapitis and Heyfords were based at the strip near Sur Masirah and in 1935 a move was made to prepare the flying boat anchorage further north. In 1942 a new area altogether was being prepared on the site of the present camp near Ra's Hilf and eventually the old bases were abandoned.

My google-fu has failed me otherwise..

Bing maps has a more detailed version of the airstrip, Google Earth also, if you go back a few years. It's not totally abandoned since there's a building of some kind that wasn't there before 2015.

I'm puzzled since the document you linked to says "Five miles up the coast, past Sur Masirah and just south of Umm Rasays, a few derelict buildings and a still serviceable concrete slipway betray the location of the flying boat base which grew up in the early years of the war to follow. "
I thought that would've been easy to find, but the airstrip you mention isn't south of Sur Masirah but north of it, so that doesn't make sense, unless the airstrip is actually the 1942 (and now abandoned) strip and the 1935 strip must be further south.

If that concrete slipway can be found we might derive the other locations from there.

 

hmm.. the document says up the coast, which kind of implies north of Sur Masirah to me anyway (I live "up North" in the north west of England - "oop north" or "darn sarf" (down south ), but google Maps (not earth) doesn't appear to show Umm Rasays... ??

However, this might be the slipway...

https://www.google.com/maps/place/20%C2%B027'45.3%22N+58%C2%B046'33.7%22E/@20.4623174,58.7595246,4501m/data=!3m1!1e3!4m14!1m7!3m6!1s0x3e9ce650a6a462bf:0x222d9b337d600d7a!2sMasirah+Island!3b1!8m2!3d20.3173398!4d58.6915912!3m5!1s0x0:0x0!7e2!8m2!3d20.4625758!4d58.7760297

The tip of this outcrop appears to show a wide flat expanse - i.e slipway for a flying boat or amphibian maybe?? The road looks a bit small though..

Might have struck gold regarding the slipways!

 https://www.agda.ae/en/catalogue/tna/air/23/635/n/45 

just need to interpret the drawing to the map because entering the coordinates appear to point to a location between Masirah and the small island Jazirat Marsays (referred to as Shagha in the document).

There seems to be a mosque here (dark circle - dome? on the roof)..

https://www.google.com/maps/place/20%C2%B028'16.9%22N+58%C2%B047'12.6%22E/@20.4713609,58.7851074,798m/data=!3m2!1e3!4b1!4m6!3m5!1s0x0:0x0!7e2!8m2!3d20.4713565!4d58.7868195

On the coast to the west is a fairly wide strip of darker coloured ground...

Much speed reading later it appears that the scanned document is 148 pages and no other diagrams exist. There's probably a fair bit of interesting reading in that lot regarding the goings on of the RAF in the 1930's.. 

I bet Tony Robinson and Time team never had these problems!! 

 

Ah, Time team, they sure knew how to make interesting TV in those days.

That "mosque" building is the only one in the area that could fit such a building. However, using the Google Earth Pro, if I go down history that mosque isn't there on 2/25/2010, at least that building is much smaller in 2010 and it doesn't have a dome (yet).
Too bad Google Earth doesn't go all the way back to 1935. Would've been much easier.

That outcrop might have been the ramp/slipway that's mentioned. The road to the outcrop looks like 6 yards wide, so not too narrow. I can't think an amphibian aircraft could've used it though, perhaps just trucks going to the outcrop.
It obviously wasn't build yet when the drawing was made in 1935, otherwise it would certainly have been included on the map.