Paul made a good suggestion!
And, this is what I would do, too!
In case you don't have a handheld GPS lying around (some smartphones / tablets have GPS built-in, as well), the short answer for you is:
You will most probably have no issues getting and holding a GPS fix with the radio
mounted below decks on a Tayana 37
FYI, here is a pic showing part of my Nav Station, where a Garmin
GPS76 is mounted...this supplies dedicated GPS position data to both of my DSC
radios (Icom M-602 VHF-DSC-FM and Icom
M-802 MF/HF-DSC-SSB)....it works great (and while I upgraded the Garmin to a slightly newer model, using the older one in my dinghy
, it's worked great like this for almost 13 years now!)