North Question Redux

Hi-

I read through the past post but couldn't seem to find a direct answer.

When setting the location in Sketchup, is the north vector that is provided to that location True North or Magnetic North?

Since solar panel are always to be oriented True South and my magnetic declanation is -15deg, I don't want to mess this up...

Thank you.

Hi John,

Setting the SU North Angle is in True Direction. (No corrections applied)

Where you can “mess up” is taking compass bearings on site and correcting them by addition or subtraction of your local (magnetic) Variation to determine the True Direction of the Compass bearings you took.

Variation is always stated as a value, East or West … Never as a positive or negative value.

Whether you add or subtract the value depends on whether you’re correcting from True Direction to Compass or from Compass to True Direction.

You don’t indicate the direction your local Variation … East or West.

-15 deg. means nothing, except an opportunity for gross error.

Use the following values to apply corrections:

Compass > True

Add East

Subtract West

True > Compass

Add West

Subtract East

Best regards,

Geo

Example 1:

Local magnetic variation is: 15 deg. EAST

The True South > Compass Bearing is:

True > Compass

Add West

Subtract East

180 (True South) - 15 (East Variation) = 165 (Compass bearing of True South)

Example 2:

Local magnetic variation is: 15 deg. WEST

The True South > Compass Bearing is:

True > Compass

Add West

Subtract East

180 (True South) + 15 (West Variation) = 195 (Compass bearing of True

South)

Pardon my roots …

Excuse any confusion by my substitution of magnetic Variation (maritime term) for magnetic Declination (rarely used in practical

navigation).

Best regards,

Geo

> Excuse any confusion by my substitution of magnetic Variation

> (maritime term) for magnetic Declination (rarely used in practical

> navigation).

>

> Best regards,

>

> Geo

Your name is Geo, of course you know about these things!

Hi Colin,

Ha Ha Ha Ha Ha !!

Rarely used skills, leftover from my misspent youth on the water.

Sailing in areas like around the Gaspe Peninsula in the Gulf of St. Lawrence, where local Variation is around 25 deg. offers a sailor but

two choices … Learn or Die.

I’m still here ... I must’a learnt sumthin’. :-)

Best regards,

Geo

Nice. Thanks for the reply. My panels are correct!