Sign in to follow this  
GregHman

Radar on a small boat

Recommended Posts

Hi guys,

I was gifted a Furuno DRS4W over a season ago, but I didn't put it on thinking my Hunter 25.5 was too small to bother with it. This time I'll be doing some much longer stretches across Lake Michigan and now I'm tempted to put it on as an extra safety device (I intend to do a fair amount of single handing).

I think it would look fairly goofy if it were stern mounted. I'd prefer to see it on the mast, but I'm unsure where. I see most radars above the spreaders, but I'm wondering if I could put mine lower within easier reach form the deck. Maybe it would be nice to not put so much weight up so high?

Any thoughts?

Share this post


Link to post
Share on other sites

The higher the better and well above head height in any case.

Share this post


Link to post
Share on other sites

Amazon says it's 25 lbs.  That's a lot of weight to have up a mast on a 25-footer.   If by "safety", you mean not running into land or other boats 12 miles away or less due to darkness or fog, a transom mount above eyeball-cooking height (research how a microwave oven works...) should do fine.

 

It looks easy enough for a skinny actress to use.  Note the mount.

 

 

Share this post


Link to post
Share on other sites

For your money, a chart plotter and AIS will do 99% of what you need.  The big boys will have AIS and it'll just be the little troublemakers that you'd want radar for.  I'd take my chances as it's the big boys I worry most about.  Small (our size stuff) can usually be avoided with a little situational awareness and a hard pull on the tiller.

  • Like 1

Share this post


Link to post
Share on other sites
3 hours ago, Veeger said:

For your money, a chart plotter and AIS will do 99% of what you need.  The big boys will have AIS and it'll just be the little troublemakers that you'd want radar for.  I'd take my chances as it's the big boys I worry most about.  Small (our size stuff) can usually be avoided with a little situational awareness and a hard pull on the tiller.

Im about to buy a gx2200 vhg with gps and ais. This is why i hesitate bothering with it. Maybe i should resell it.

I haven't done enough sailing on lake michigan to know if there is much fog.

 

Share this post


Link to post
Share on other sites
3 hours ago, atoyot said:

Amazon says it's 25 lbs.  That's a lot of weight to have up a mast on a 25-footer.   If by "safety", you mean not running into land or other boats 12 miles away or less due to darkness or fog, a transom mount above eyeball-cooking height (research how a microwave oven works...) should do fine.

 

It looks easy enough for a skinny actress to use.  Note the mount.

 

 

Why not do the same height on the mast? Pole mounts may look really silly on the hunter 25.5 unless i added more doodads like a wind generator and solar

Share this post


Link to post
Share on other sites

I agree about the AIS idea, but make sure the VHF with AIS that you're thinking about is a transceiver and not just a receiver - you want them to see you and you them (transmit and receive), not just receive for the safety aspect to work.

Greg

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, GregHman said:

Im about to buy a gx2200 vhg with gps and ais. This is why i hesitate bothering with it. Maybe i should resell it.

I haven't done enough sailing on lake michigan to know if there is much fog.

 

+1, I find AIS to be more useful (where we sail) than radar for offshore collision avoidance.

Share this post


Link to post
Share on other sites

AIS Transceiver and Chartplotter - big boys off the entrance of NY could see me very easy in 10-15 ft swells at night.  I am adding two PLBs this year to my boat for crew on deck.

Share this post


Link to post
Share on other sites
12 hours ago, IStream said:

The higher the better and well above head height in any case.

Yah..high is good .  Dont know your boat and dont know your radar size 

 

google "class 40 " for pictures...these race boats  rely on radar and gimbale  mount the radar for best reception and best sailing performance 

 

IMG_8544.JPG

IMG_8543.JPG

Share this post


Link to post
Share on other sites
8 hours ago, GregHman said:

Maybe i should resell it.

I would. Put the money towards AIS (and I agree with gcutter about the desirability of a transceiver rather than a mere receiver).

Share this post


Link to post
Share on other sites

You would be surprised how many small and midsize  boats who are not fit with AIS.

radar is a beutiful tool if you need all weather navigation 

if I had to choose the most important tool...gps, chartplotter, ais , radar ...it would always be the radar.

  • Like 2

Share this post


Link to post
Share on other sites
5 hours ago, slug zitski said:

google "class 40 " for pictures...these race boats  rely on radar and gimbale  mount the radar for best reception and best sailing performance 

This is exactly what I as thinking. I would mount it just high enough for me to reach to take down when I step my mast each year. I wasn't planning on a gimbal out of cost and I don't need to see much past 3 miles... I plan ahead and look up for weather...

5 hours ago, Svanen said:

I would. Put the money towards AIS (and I agree with gcutter about the desirability of a transceiver rather than a mere receiver).

I'm pretty fond of sticking with the GX2200. Hailing features are nice and navigating to a waypoint and using traditional charts seems like all I would need to sail on Lake Michigan. My tablet and phone are backup and they do as good a job of any chartplotter for getting around.

Is there a "low cost" transponder out there? I'm thinking I could just slap a small stern mounted antenna on my stern.

I'm fond of reducing the amount of permanent electrical items on my 25ft boat, staying economical, and being safe as I start to single-hand more. I was going to buy a GX2200 and I have a backup mounted VHF, backup handheld HVFs, and a PLB that stays attached to my PFD.

 

Share this post


Link to post
Share on other sites
15 hours ago, GregHman said:

Why not do the same height on the mast? Pole mounts may look really silly on the hunter 25.5 unless i added more doodads like a wind generator and solar

Your boat - your choice, Captain. You asked for opinions.   The net result either way will be that you're better off with the extra safety gadget than without, assuming the same set of skills with or without it.

As you've said since this post that you're mainly looking at 3 miles out, whatever you do that's safe, should be fine.

If you do go and mast-mount it within reach for ease of seasonal mast stepping/unstepping, just know that our warnings about mounting a few watts of pulsed, microwave transmitter RF are not idle suggestions.  If it's too convenient to reach, it might be too low for safety where near-field RF exposure is concerned; I guess this supports your mast placement preference after all....

Best wishes in the coming season.

Share this post


Link to post
Share on other sites

before you get too wound up on mounting the radome, though the cautions are MOST APPROPRIATE,  where are you going to place the display ? 

If you are single handing, you will want to be able to see it while at the helm, and reach it to change ranges etc. 

The obvious locations are either the cabin bulkhead, or a panel in your companion way. 

Make sure you can operate with one hand while steering and making a radio call with the other 2.... 

 

 

Share this post


Link to post
Share on other sites

Below is a photo of a setup on a Hunter 25.5 (not my boat or photo; it is taken from an advert on Sailingtexas.com).

69F36E7A-2E07-4DC5-A4ED-8D7D2711CD77.jpeg.f5310b3c9bec6d6e0662c2099f1e7418.jpeg

A few comments, for what they may be worth: (1) all this kit on a small Hunter seems a bit much; (2) while I appreciate that it is possible to drown in a bathtub, Lake Michigan is not a hugely challenging sailing environment; (3) safety is generally achieved not by stockpiling electronic gadgetry, but rather by prudent judgment and seamanship.

If I were the OP, I would eschew radar, chart plotter and AIS. All are certainly nice to have features, but really unnecessary for his intended application.

Share this post


Link to post
Share on other sites
3 hours ago, LionessRacing said:

before you get too wound up on mounting the radome, though the cautions are MOST APPROPRIATE,  where are you going to place the display ? 

If you are single handing, you will want to be able to see it while at the helm, and reach it to change ranges etc. 

The obvious locations are either the cabin bulkhead, or a panel in your companion way. 

Make sure you can operate with one hand while steering and making a radio call with the other 2.... 

 

 

Here's the deal.  IF you're going with radar, it just doesn't make sense to have a separate display.  A radar 'should' overlay on your chart plotter.  Since you're already 'gifted' with the Furuno,  get a chart plotter that will take the radar signal if at all possible. If it doesn't, you've added extra electrical consumption and extra bulkhead/pedestal real estate for a 2nd display.  I 'might' even just go with the chart plotter and AIS and only add the radar if you find that you 'missed' having it.  After all, it was free anyway and sometimes free, well, really isn't....

Share this post


Link to post
Share on other sites

An overlay is fine, but to make it work reasonably, requires a “good” rate compass so that the heading changes are nulled out. 

An sufficiently large daylight viewable MFD with $800 heading sensor, E charts, AIS input, DSC VHF link etc quickly gets into $1000s. 

Installing the gifted radar standalone, with an eye toward future system use is sensible, just plan on it so that you have a functional system that meets your needs. 

Share this post


Link to post
Share on other sites
6 hours ago, atoyot said:

If it's too convenient to reach, it might be too low for safety where near-field RF exposure is concerned; I guess this supports your mast placement preference after all....

I was just comparing the height of the two common mounting methods: mast and stern pole.

Share this post


Link to post
Share on other sites
8 hours ago, GregHman said:

I was just comparing the height of the two common mounting methods: mast and stern pole.

Your problem is that the boat is so small.

difficult to over come.

 

you might consider a radar,   mast mounted on a spinnaker track car.  In normal mode radar down ,  on deck.  

In broadcast navigation mode radar hoisted to top on spi pole track .

a stern pole, mast, tower,  can work .  But on a twenty five footer they would be an eyesore and complicate docking maneuvers.

the mast mount is exposed to tacking jibs.

Share this post


Link to post
Share on other sites
18 minutes ago, slug zitski said:

mast mounted on a spinnaker track car

That's an interesting thought. Sounds like a lot of holes and I would need to do something clever with the wiring. It seems like I should be able to fix it to one point and get the best of both worlds without being in the microwave beam.

I guess I need to look the beam angles and figure out the minimum heights to keep people in the cockpit from being in the path.

Share this post


Link to post
Share on other sites

Be very conservative with the nominal beam angle and the resulting minimum height you calculate. There's diffraction effects, reflection off nearby metal surfaces, etc that also come into play. Yes, it's just a fraction of the power but still. If you mount it directly overhead or close (i.e. on a pole behind the wheel), you can safely ignore those issues. If you mount it forward of your head, add a very generous safety factor to the minimum height you calculate. As I said above, the higher the better for reasons of both performance and safety. If the weight aloft is unacceptable, I'd second the idea of selling the unit and investing in an AIS transceiver. 

Share this post


Link to post
Share on other sites
24 minutes ago, IStream said:

Be very conservative with the nominal beam angle and the resulting minimum height you calculate. There's diffraction effects, reflection off nearby metal surfaces, etc that also come into play. Yes, it's just a fraction of the power but still. If you mount it directly overhead or close (i.e. on a pole behind the wheel), you can safely ignore those issues. If you mount it forward of your head, add a very generous safety factor to the minimum height you calculate. As I said above, the higher the better for reasons of both performance and safety. If the weight aloft is unacceptable, I'd second the idea of selling the unit and investing in an AIS transceiver. 

Vertical beam is 25deg. There is 15ft from mast to stern. Tan(12.5deg)*15ft=3.3ft or more conservatively 7ft if all of the beam was pointed down (25deg). Lets add 7ft to that for someone standing on the transom and you get you get 14ft.

Thoughts?

Share this post


Link to post
Share on other sites

Keep in mind that the nominal beam angle is generally defined at the half power point, so your increase of 3.3' to 7' isn't a bad thing but also isn't really conservative. Standing on the transom with the unit mounted 7' up would still expose your head to something approaching half the power of the beam. Adding the factor of two by moving it up to 14' sounds reasonable.

Share this post


Link to post
Share on other sites
4 hours ago, GregHman said:

That's an interesting thought. Sounds like a lot of holes and I would need to do something clever with the wiring. It seems like I should be able to fix it to one point and get the best of both worlds without being in the microwave beam.

I guess I need to look the beam angles and figure out the minimum heights to keep people in the cockpit from being in the path.

The one i saw used the spi pole track..the radar was mounted on a composite sadle with a spi pole car and could travel up and down the track 

 

the wire was inserted into a rope cover...one end spliced to the bottom of the radar saddle ..one end spliced to a deck pad eye  at the mast base .

the radar was hoisted until this wire core rope down haul was tight 

the wire penetrated the deck near the mast with a gland 

the system looked like it worked 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this