Where to mount radar dome?

[Steve Laume]

Any experience with pros and cons of various radar mounts? Mast mount: weight aloft, good elevation, wiring at rigging time. Pole mount: weight in the stern of the boat, low, might make a good place to mount a lifting davit for the dog. Back stay: ??? I think the mast is cheapest. Opinions and options would be appreciated, Steve.

[steve einhorn]

Did you figure out your question. I am considering putting radar on my 26D but the 18' dome may interfere with the jib when I tack. Any suggestions

[Parfait's Provider]

Some people think that I might fry my brains, but it is 8 ft. above the deck and I am usually either sitting or standing in the cockpit so the beam is well overhead. Access is easy, just stand on the pushpit. Weight really isn't all that much compared with al the junk in the lazarette. Wire routing is simple. There is nothing that can catch on the dome easily.

Range is probably a little shorter than 20 feet higher, but RADAR isn't perfect even at 2 miles, so why worry about 15 vs. 20?

BTW, if you want to be seen by another boat, get a reflector and fly it high.

[Bill Cochrane]

Have about decided on the stern mounted pole as well. Reasons:

- Mast mount: Higher, out of way; also hard to access, issues with some foresails, wanted to avoid cutting and connectorizing cable which is needed for mast removal (not all that often, though). Possible to use swivel mount but see backstay mount comments. Height and location forward limits close-in range; height increases distant range slightly. I want to see crab / lobster pots as close as possible and believe the tradeoff in distance is reasonable.

- Backstay mount: My initial choice; rigger assured me that the additional side loads on backstay were nothing of concern. Was mainly dissuaded by unfavorable comments about manufacturer support from one of the companies, and some reported QC/reorganization issues with the other company. While not a primary consideration, this is also the most expensive route. Aside from that, this is the "cleanest" install in terms of non-interference with rigging or sails (compared with mast mount) and use of limited deck space (as opposed to pole). Cable run is simple and there is no need to splice.

- Pole mount: Narrow stern deck area makes this a bit tricky and I need to carefully plan the location of the pole and support struts so as not to interfere with mooring chocks and cleats, cowl vents, lazarette hatch, outboard mount, etc., but I think it can be done. I will probably go with a design from Kato marine that provides a manual tilt capability that's easy to adjust and very reliable. Comments regarding height, radar range and cable run are the same as for the backstay mount.

The Naval Academy chose stern pole mounts for their fleet of 44' sail training boats, for what that's worth. Those boats are used for coastal cruising and participate in the Bermuada races.

Ditto on the radar reflector comments...I have a Davis corner reflector for each of the two signal halyards and fly one or both just below the spreaders.

Regards, Bill

[Steve Laume]

I went with the mast mount and hope I do not regret it after it is all installed and I begin to use the boat. I must admit that price was a major factor in the decision. After buying radar, chart plotter, upgraded charging and monitoring system and some used sails my boat budget is more than gone for this year. Other than price I felt that the mast mount was very simple and easy to install. It is the cleanest looking installation. It gets that nasty radiation well away from anyone on board. Weight off of the stern and up high at that. A few less holes to caulk. It will not become a shade problem for possible future stern rail mounted solar collector. The stern pole would also interfere with fighting fish from the cockpit. The mast mount would also be the easiest to change if it does not work out but then once something is done I hate to change so I doubt it will ever be relocated. There were a lot of things I liked about the stern pole but the mast mount is sitting in my kitchen and ready to go. If money were no object the stay mount would look very good, Steve.

[Joe Mac Phee]

Steve,

My CD-30 spends the summer with her stern bootstripe in the water. I am on a mad rampage to get weight out of the stern. I moved a 4D battery into the vee berth area, and I am still looking for things to move (or remove).

From a trim perspective as well as radiation safety, I think you did the right thing to go for mast mount (that is where mine is).

My radar is from Raymarine and I was able to find an extension cable that allows the mast to be removed without cutting any cables. You could also (for much less money) just mount a terminal strip inside.

It is getting warm in New England! I am working on my mast in a tee shirt instead of a down parka.

Joe Mac Phee

[Parfait's Provider]

Joe,

Some boats carry chain and sand in the forepeak to lift the stern.

[Steve Laume]

Ken, putting more weight in the bow doesn't lift the stern. It sinks the bow. I am leary of adding weight in the ends after a few examples I have seen. I bought a Typhoon that had a 8HP engine with a generator on it. I can understand what the PO was going for in the way of recharging his batteries. The only problem was that the motor weighed so much he had to put about 80LBS of lead up forward. Then he raised the water line up to the top of the boot strip as the boat sank that much to be in balance. The best example is rowing two people in a small dink. To balance the boat you sit bow and stern. It makes for an even keel but a very unstable ride. I know this is an extreme example but the principal is still the same. White water canoes are probably the best lesson I have learned in balance. If paddling tandem you want to move both seats near to the center of the boat. The air bags go in the bow and stern. This makes for a very stable boat even when partially swamped. Much more maneuverable and stable when dry than having the seats in the ends. To counteract all of this good distribution of weight I really like to stand up on the aft deck while holding onto the backstay. It gets me up a little higher and I can watch the whole boat move before me. It is a magical ride and one more reason not to have that radar to low at the stern, Steve.

[Neil Gordon]

Ken, putting more weight in the bow doesn't lift the stern. It sinks the bow.

Yes and no. There are two factors at play here.

Add weight and you displace more water. That partially sinks the boat overall. Add that weight at the center of balance and you'll evenly lower the waterline. Search through some old threads if you really want to know by how much.

Move that weight around so that it changes the center of balance and you change the trim of the boat. Everything else being equal, move weight to the stern and the stern goes down while the bow goes up.

Add weight to the bow to compensate and two things happen. Trim is resored, which lowers the bow a lot (relatively). The waterline is once again lowered (a little).

Point well made is that weight towards the center of the boat and buoyancy at both ends makes for a better ride. (Also a good reason for the helmsperson to be able to sit as far forward in the cockpit as possible.)

[Parfait's Provider]

Well sure, it sinks the whole boat, but the stern will still be higher than it used to be. If not, then when the two of you stand on the bow of your dink, the stern would still be in the water. You know better than that.

As for keeping weight out of the ends, I totally agree with that; I was feeling kind of frisky and thought you would see the tongue in my cheek.

Good luck with getting all that "stuff" out of the lazarette.

[Neil Gordon]

As for keeping weight out of the ends, I totally agree with that; ... Good luck with getting all that "stuff" out of the lazarette.

So the best way to get the boat back in trim would be to move the spare anchor(s) from the lazarette to the cabin floor?

[Joe Mac Phee]

If I take beverage out of the midship reefer, sit at the helm in the stern and consume it, and then use the head which empties into the holding tank under the vee berth, would this affect trim?

Joe Mac Phee

[Neil Gordon]

If I take beverage out of the midship reefer, sit at the helm in the stern and consume it, and then use the head which empties into the holding tank under the vee berth, would this affect trim?

It's worse than that. Not only does weight get redistributed from midships to stern and then to bow, but *some* of the weight is may be permanently retained by the helmsperson. Then, as the reeer is restocked, (notwithstanding pumping the contents of the holding tank) the boat will settle ever lower into the sea.

[s.v. LaVida]

We put a radar mast (9') on LaVida's starboard stern. It has proven to be a good choice. I know we lose some horizon when heeled but overall, its worked very well there.

I was never a fan of having the radar unit smacked each time I tack. Tacking our 150% genoa, destroyed my AquaSignal light. I had to put a guard around it. Just thinking what it would do to a radar unit persuaded me to opt for the stern radar pole.

We used Scan Strut and really liked their quality.

While we were at it, I mounted a deck light on the radar mast and now have a great cockpit lighting when needed.

Rit

[Cathy Monaghan]

Hi Steve,

Any experience with pros and cons of various radar mounts? Mast mount: weight aloft, good elevation, wiring at rigging time. Pole mount: weight in the stern of the boat, low, might make a good place to mount a lifting davit for the dog. Back stay: ??? I think the mast is cheapest. Opinions and options would be appreciated, Steve.

If this helps, take a look at this old posting on this board which includes some photos of my CD32 and her mast-mounted radar dome.

http://www.capedory.org/board/viewtopic ... 3940#83940

The radar is mounted about a couple feet below the spreaders and the staysail just clears it. Our radar dome is attached to the mast via a gimballed mount by Questus which has worked very well. Currently the wiring terminates at a terminal block below the deckmounted mast step in the head. And the mast was unstepped in the fall without a problem. But one of this year's projects is to replace the terminal block with a coupling which will make connecting/disconnecting the radar interunit cable easier.

Hope this helps,
Cathy
CD32 Realization, #3
Rahway, NJ
Raritan Bay