My wife and I do a fair amount of sailing out in Buzzards Bay, Long Island Sound, or out to the Vineyard and on occasion and have been caught in fog midway thru a trip, not a fun situation without radar. I have a GPS chartplotter to limp thru this unpleasant situation when it happens but the risk of not knowing what other craft are out there is something I need to address. As a result I plan to add radar to my boat over this winter storage season and wonder if anyone out there has found an aftermarket source for mounting a radome antenna off the rear of the arch so I can eliminate the need for a mast mount or stern pole mount. I am thinking that a stainless frame that would wrap around the underside of the arch tubes and be gasketed and bolted in place would be a great solution and still allow free movement of the traveler across the top of the arch. Thanks, Bruce
- Status
From What I Understand...
Thurston in Bristol does a great job "working out a way" to do this type of thing. The three brothers each have an industry niche - sails, canvas and welding. I have had them do sail and canvas. And I have seen their welding enginuity next to me at the marina - superb work (if not a bit pricey), but worth it! Or...you can also check with Hunter (Sailing Specialties) in Bristol for the same type of work.
Thurston in Bristol does a great job "working out a way" to do this type of thing. The three brothers each have an industry niche - sails, canvas and welding. I have had them do sail and canvas. And I have seen their welding enginuity next to me at the marina - superb work (if not a bit pricey), but worth it! Or...you can also check with Hunter (Sailing Specialties) in Bristol for the same type of work.
Radar mount- not on the stern!
Having used radar and taken training in it's use I would not recommend installation on a stern mounted pole. Consider the following in making your decision: The beam emittd angles both downward and upward; anyone on the deck perhps forward of the cockpit will be exposed to the effects of the transmission. Secondly the higher the unit can be mounted, your ability to see targets to the maximum of the range of your unit is enhanced.
Having used radar and taken training in it's use I would not recommend installation on a stern mounted pole. Consider the following in making your decision: The beam emittd angles both downward and upward; anyone on the deck perhps forward of the cockpit will be exposed to the effects of the transmission. Secondly the higher the unit can be mounted, your ability to see targets to the maximum of the range of your unit is enhanced.
Another opinion on stern mounting
I have a 4KW Raytheon radar mounted on a backstay well above the head of anyone in the cockpit. According to Raytheon manuals this height (above heads) is preferred. I had an opportunity to speak to a Tech at Raytheon and asked about exposure to people on the foredeck. His reply was that anyone in the line of transmission and beyond a few feet from the radome was safe. He further went on to say that radation exposure was greatly overhyped. He told me that for recreation marine radars to present a personal radiation hazard you would have to rest your head against the radome for quite some time at full power. Take it for what it's worth. BTW, this is NOT true for military radars that put out thusands of KW in a very focused beam. Regarding the height of mounting- The theoritical range in nautical miles to the water surface is figured by the formula 2.23 times the square root of the height of the radome in meters. Thus mounting the radome on the arch would be at least 3 meters off the water providing a range of 3.9nm. Mounting up on the mast at 8 meters (24') the range would be 6.3nm. Since targets (buoys or boats) are higher than the water surface, the range is increased by the same formula using the target height in meters. Land masses are typically higher yet. Most uses for radar is to see those targets that are close enough to hit. Four miles is adequate for a very small target. I use my radar on the 1.5nm range most of the time. The one real use for a long range is to look for thunderstorms. Here the height of the radome is not important because the heigth of the thunder storms is thousands of feet and you can see them easily at 40-50 miles away. Large fast-moving tugs with tows can be seen with a 3 meter radome at 10 miles. A case can be made for a low mounting of the radome so that you can see targets that are close to you. Since the radar beam is typically 12.5 degrees above and below the horzontal, the closest point (in feet) that you can see is the heigth (in feet) divided by the tangent of 12.5 degrees. For a radome at 3 meters (9') that distance is 40'. For 8 meters (24') the range is 108'. If you are picking your way through a tight channel in dead fog it would be better to see buoys on your port and starboard down to 40' instead of 108'. Anyway, the choice is yours. There are trade-offs for every choice. Be informed.
I have a 4KW Raytheon radar mounted on a backstay well above the head of anyone in the cockpit. According to Raytheon manuals this height (above heads) is preferred. I had an opportunity to speak to a Tech at Raytheon and asked about exposure to people on the foredeck. His reply was that anyone in the line of transmission and beyond a few feet from the radome was safe. He further went on to say that radation exposure was greatly overhyped. He told me that for recreation marine radars to present a personal radiation hazard you would have to rest your head against the radome for quite some time at full power. Take it for what it's worth. BTW, this is NOT true for military radars that put out thusands of KW in a very focused beam. Regarding the height of mounting- The theoritical range in nautical miles to the water surface is figured by the formula 2.23 times the square root of the height of the radome in meters. Thus mounting the radome on the arch would be at least 3 meters off the water providing a range of 3.9nm. Mounting up on the mast at 8 meters (24') the range would be 6.3nm. Since targets (buoys or boats) are higher than the water surface, the range is increased by the same formula using the target height in meters. Land masses are typically higher yet. Most uses for radar is to see those targets that are close enough to hit. Four miles is adequate for a very small target. I use my radar on the 1.5nm range most of the time. The one real use for a long range is to look for thunderstorms. Here the height of the radome is not important because the heigth of the thunder storms is thousands of feet and you can see them easily at 40-50 miles away. Large fast-moving tugs with tows can be seen with a 3 meter radome at 10 miles. A case can be made for a low mounting of the radome so that you can see targets that are close to you. Since the radar beam is typically 12.5 degrees above and below the horzontal, the closest point (in feet) that you can see is the heigth (in feet) divided by the tangent of 12.5 degrees. For a radome at 3 meters (9') that distance is 40'. For 8 meters (24') the range is 108'. If you are picking your way through a tight channel in dead fog it would be better to see buoys on your port and starboard down to 40' instead of 108'. Anyway, the choice is yours. There are trade-offs for every choice. Be informed.
- Status