7X50 for marine binoculars is chosen for some very good reasons as being the best compromise of all the variables. Unless you can find a decent monocular at 7X50 I suspect you best answer is a pair of decent binoculars with the redundant eyepeice blanked off.
I had two pair of binoculars that had become misaligned. 12 x 50 and 10 x 50. I separated them and made 4 monoculars. Two of them have the central adjustment and the other two have spacers added to the centre section for focus. I have a 10 x50 in my yacht, one kept in the house and the other two are in my cars. The 10 x 50 is easy to use at sea, I hold on with one hand and push the prism section firmly into my cheek or nose and its easy to keep steady. Beats any binoculars!
Sounds perfect Thanks, this is now on my watch list
I thought I'd cracked it when I bought an old pair of Colmont Senator 8x32 (made in Paris) for less than £10 off e-bay
They have individual focus for each side so I figured they'd be ideal added bonus when dialed in carefully they force my wandering eye to centre sadly prolonged use this way makes me very susceptible to motion sickness so I have close one eye