Hi Shaun,
As SW has stated DEMS are very difficult to research and a different approach is usually needed. Service records should always be your first port for any serviceman but they don't give a breakdown of detached duty to DEMS i.e. individual merchant ships.
One approach is to use Crew Agreements of a known ship if this ship is at the end of his service all the better as you have the possibility of using those Crew Agreements to back track his service from that known ship to his previous ship etc. and with a bit of luck you may get somewhere. Be aware though that this method does have its drawbacks and your research can come to a dead end quickly if a previous ship was a war loss and shore copies [of crew listings] are in any way incomplete. You may or may not be lucky with the ship HELVETIA, she was Dutch and you will just have to see if the C.A is available and shows he was aboard and also names his previous ship.
If the C.A. for HELVETIA is not available you can try Henk Meurs, an expert on the Dutch Merchant Navy. I had no reply previously when using his email address but you can post on his facebook here:
http://members.ziggo.nl/hmeurs/ he does hold Dutch crew lists.
Another method would be to go back to the MOD and request his Pay & Victualing Ledger which may give a breakdown of his actual [merchant] ships - The MOD holds Royal Navy Pay and Victualing Ledgers up to 1951. Give them his service number and request his P & V Ledger and state he was a DEMS gunner.
navysearchpgrc[AT]tnt.co.uk [email address altered for obvious reasons]
Director Naval Personnel,
TNT Records Management,
PO Box 7814,
William Nadin Way,
SWADLINCOTE,
Derbyshire,
DE11 1EG
As a caveat this method does not always work and you can then go down the road of a Freedom of Information request to the MOD, again not always successful, but leave no stone un-turned is my motto.
Let us know how you get on - good luck.
Regards
Hugh
