Spreader mounting a Radar dome

[bgraham]

I looking at purchasing a Garmin GMR18HD for my 40 foot boat. I'm was going to purchase a mast mount for it, but as I socially race the boat, I'm concerned about the foresail being caught in the radar. I'm considering mounting the Garmin on the upper spreader, and wonder if anyone has tried this, is the radar performance compromised?

Thanks in advance

Bob

[sailingdog]

I wouldn't. The spreaders really aren't designed to have that kind of weight on them. If you mount the radome on the mast and put a proper radar guard on the radome, the genny won't get caught on it.

[Maine Sail]

I have used and sailed many, many boats with mast mount domes. If you let the sail tack itself through the triangle, then pull the sheets, you'll rarely if ever have an issue. If you just start yanking on the sheets before the sail has naturally brought her self across you WILL tangle a dome..

In the last 20 years or so I have only caught the head sail once and that was on a mast mounted spin pole.. I would not mount it on a spreader. You may also get a larger radar shadow to one side or the other because the mast is deeper than wide and the radome would be looking through the widest part of the mast section.

P.S. In the normally light Maine summer winds I usually run a #1 (150 genny) and still never had an issue with catching my sail...

[svHyLyte]

Aside from the fact that the weight of the radome is not something you want to introduce to a spreader, particularly when it's to leeward, the loss of signal to the mast will not be insubstantial. The same is true to some extent of a radome mounted forward of the mast but, as the side-to-side dimension of the mast is usually a lot less then the fore'n aft dimension, the effect is lessened; and, a target approaching from astern is somewhat less of a hazard than a missed target approaching from one's [blind] side. To give yourself an idea of the cone of blindness, cut a disc out of cardboard the same dimension as your radome and position it on deck, beneath the spreader, as far outboard of the mast as it would be if it were actually mounted on the spreader Then draw straight lines between the center of the disc and the fore and aft edges of the mast. The resulting cone, radiated outward from the mast to port or starboard, will be your effective cone of blindness.

With a proper mast mount, your mast-mount and sail will have little interaction.

FWIW…

s/v HyLyte

[bgraham]

Thanks for your advise, I'll go the mast attachment route

Regards

Bob