Handbearing compass on steel yacht?

[jerrytug]

I love using handbearing compasses, I own several and always have one dangling round my neck if I'm under way.

I have my eye on an all steel cruising yacht, and wonder how steel yacht owners get on?

My reasoning is, the gigantic deviation would stop you getting 3-point fixes properly, or doing running fixes etc.

But for collision avoidance, deviation wouldn't matter, as the change of bearing, or not, is what you are looking for.

Any compass experiences to share on your steel yachts?

(she has an old-fashioned steering compass with a compensating bar, mounted on the hatch garage, which looks to be best spot for deviation and being able to steer by the compass)
cheers Jerry

 

[Egbod]

I understood that you used a sighting device on the ships main corrected compass.
Is one available for the compass that is fitted?

 

[Uricanejack]

It’s a common misconception HBC are not affected by deviation. They are just like any other compass the problem is not being in a fixed location they cant be adjusted or have a reliable deviation card made.

On wood and glass boats the effect of deviation is usually small enough to be ignored.
On a steel boat the effect is going to be there.

The best thing is to fit a binnacle on the centerline high enough to use an azimuth ring or similar for bearings
This compass could be adjusted. This was available on all the steel vessels I have been on.
If this is not practical
A few things you can do.
Use your HBC from directly above your steering compass location, the deviation should be about the same or close enough for the difference to be ignored.
Take bearings from the centerline. If you are on one side your deviation will be unsymmetrical.
If you pick a regular position to use your HBC on the centerline you can make rough card by comparing cardinal and intra cardinal headings to your steering compass
Compare with compass heading and HBC heading every time. Then use the steering compass card. Effectively your HBC is like a pylorus.

Or if you have time a bit further offshore and want greater accuracy.
Use your HBC like a horizontal sextant. Use the differences between the bearings the error will be constant.

Oddly I have never used a station plotter. But I would think one would work in this case. So long as you take all the bearings from the same position on the boat.

 

[jerrytug]

I understood that you used a sighting device on the ships main corrected compass.
Is one available for the compass that is fitted?

Hi Egbod, that's right, but unfortunately the position of the compass, and the motion and heel of a nine ton sailing boat, may make it difficult a lot of the time, cheers Jerry.

 

[jerrytug]

It’s a common misconception HBC are not affected by deviation. They are just like any other compass the problem is not being in a fixed location they cant be adjusted or have a reliable deviation card made.

On wood and glass boats the effect of deviation is usually small enough to be ignored.
On a steel boat the effect is going to be there.

The best thing is to fit a binnacle on the centerline high enough to use an azimuth ring or similar for bearings
This compass could be adjusted. This was available on all the steel vessels I have been on.
If this is not practical
A few things you can do.
Use your HBC from directly above your steering compass location, the deviation should be about the same or close enough for the difference to be ignored.
Take bearings from the centerline. If you are on one side your deviation will be unsymmetrical.
If you pick a regular position to use your HBC on the centerline you can make rough card by comparing cardinal and intra cardinal headings to your steering compass
Compare with compass heading and HBC heading every time. Then use the steering compass card. Effectively your HBC is like a pylorus.

Or if you have time a bit further offshore and want greater accuracy.
Use your HBC like a horizontal sextant. Use the differences between the bearings the error will be constant.

Oddly I have never used a station plotter. But I would think one would work in this case. So long as you take all the bearings from the same position on the boat.

Thanks Jack, a couple of good points there which I hadn't thought of..

Comparing the main compass and the HBC every time and writing down the difference, and

using the HBC like a horizontal sextant.
I will have to dig out some dusty old books to remind me about the second one... cheers Jerry

 

[[70521]]

Pehaps a handheld GPS with compass might solve a problem.

 

[KellysEye]

We had a HBC and steel boat, we found if you stood on a cockpit seat holding on to the boom it worked fine. The main compass should be a flux gate compass low down at the centre of the boat.

 

[jerrytug]

We had a HBC and steel boat, we found if you stood on a cockpit seat holding on to the boom it worked fine. The main compass should be a flux gate compass low down at the centre of the boat.

Thanks. But I don't get that. Fluxgate compasses are equally affected by dev and variation, so why is it best to have them low down in the middle, , where they are close to, and enclosed by, literally several tons of steel?
I'm not being argumentative, I just can't see why it would be best?

 

[rogerthebodger]

The reason for mounting a flux gate compass low down it to keep it as close to, the centre of pitch and roll as possible and yes the steel dose have an effect but it can be compensated for in the same way as a normal magnetic compass but electronically as in my case.

 

[jerrytug]

The reason for mounting a flux gate compass low down it to keep it as close to, the centre of pitch and roll as possible and yes the steel dose have an effect but it can be compensated for in the same way as a normal magnetic compass but electronically as in my case.

I see that's very interesting. I presume you have a digital compass display in front of the helmsman? And the compass displays the ship's head in degrees magnetic, because the deviation is electronically removed?
Clever stuff.

 

[Halcyon Yachts]

I always favour using a hand held compass to assess if a risk of collision exists, and always have one to hand when on board any vessel. For this deviation doesn't matter as you are just looking for a change in bearing.

I can't remember the last time I used one (other than when I'm teaching) to fix a position. The GPS always seems to do it so much more accurately and quicker!

Pete

 

[jdc]

...I can't remember the last time I used one (other than when I'm teaching) to fix a position. The GPS always seems to do it so much more accurately and quicker!
Pete

Only if there's a chart with a known relationship to WGS84. This may sound like a nit-picking answer, but we have had occasions this year while navigating 'on the white' when only clearance bearings are available from pilotage notes, and in some places the charts are accurate enough in a relative way but displaced from the GPS positions by unknown and significant amounts.

I know that commercial - presumably steel - vessels use their radars under these circumstances to do distance-off fixes rather than angular fixes.

 

[rogerthebodger]

My flux gate compass is mainly for my autopilot and that does display in digital format but I do also have an electronic compass display viewable from boat inside and outside steering position. This display is a dial type compass display.

I also have a conventional magnetic compass at my cockpit help with big black correction balls mounted on each side adjusted every so often.

 

[lw395]

I would not want to be without a hand bearing compass on a steel boat.
Neither would I expect it to be very accurate.
I've twice been on steel boats and needed a rough check on the main compass, in fog.
GPS is no use once you are stopped or going 1 knot or so.

 

[TQA]

I was naive about navigation when I started cruising on my 38ft steel boat. I had my Seastrel Moore compass professionally adjusted, then I had Jenny drive the boat in different directions boxing the compass and holding briefly on each point while I was standing up holding the mizzen with the hb.. I noted the reading on the handbearing compass and made a deviation table for the handbearing compass. I did not know if this was technically correct but it seemed to work OK.

 

[Uricanejack]

I was naive about navigation when I started cruising on my 38ft steel boat. I had my Seastrel Moore compass professionally adjusted, then I had Jenny drive the boat in different directions boxing the compass and holding briefly on each point while I was standing up holding the mizzen with the hb.. I noted the reading on the handbearing compass and made a deviation table for the handbearing compass. I did not know if this was technically correct but it seemed to work OK.

Should have worked just fine so long as you took your bearings from the same position just in front of your mizzen. Rather than being niave. I'd say you applied commonsense and good judgement to solve a problem.