Draft: Bare or Loaded?

How long ago did you contact GW? They're usually pretty good at getting back to people.

Anything stated in boat (and manufacturer) manuals, if not specifically specified, will always be bare. I do not know of any way to "estimate" the increase in draft with a loaded boat. Most likely, your boat sits a little deeper than 18" to start with since it's 23 years old is probably a little heavier due to moisture absorption. Overall, though, I don't think from bare to loaded will be more than 6" - I think that would be a safe guess, anyways. Measure it and see!

This is not scientific at all but you can make an estimate which will get you an approximate scale of change.
If the hull was square and flat and the additional load was evenly distributed, then estimates would be pretty close.
Since loads are not generally evenly distributed and hulls are not square and flat. The estimates is a lot more complex but let's give it a try. Lets say the bare hull weighs 5000 pounds. If the hull were flat and uniform in shape ( square, rectangular, round, it doesn't matter) then an 18 inch draft would equate to 278 pounds per inch of displacement.
Add 1000 pounds of gear and the hull will sit a little over 3 1/2 inches lower.
In the real world, hulls are not flat and V hulls actually present more hull to the water as they sit lower. That will reduce the inches per extra weight. At the same time the stern is a bigger area to the water so weigh added up front can have a larger effect than weight added in the rear

Just keep an eye on the color of the water ahead, remember this, and you wont have to worry about your draft:

Brown, brown, run aground!"

When in the water, make a mark, or a mental note, where the water line is. On the trailer, measure from that mark to the ground, and subtract from the ground up to the bottom of lower unit. That is your actual draft at float. On plane or plowing will differ.

Finest Kind said:

Just keep an eye on the color of the water ahead, remember this, and you wont have to worry about your draft:

Brown, brown, run aground!"

Click to expand...

That works in Bermuda but not so much in Jamaica Bay NY. At times all the water is brown and it is rarely blue

It's true that all hulls absorb moisture over time. But, in "normal" cases, the amount of weight it's going to add VS how much deeper a boat sits is not going to be a whole lot. But, I was/am unsure how accurate of an answer you were looking for - which is why I offered that.

I'm curious - why the need to know such a specific number? Can you not just add the weight (even "fake" weight such as sand bags, water in coolers, etc), get in the water (in a calm area) and measure it? After all, it's not like you're expecting some snow today, like we are in PA!

seasick said:

Finest Kind said:

Just keep an eye on the color of the water ahead, remember this, and you wont have to worry about your draft:

Brown, brown, run aground!"

Click to expand...

That works in Bermuda but not so much in Jamaica Bay NY. At times all the water is brown and it is rarely blue

Click to expand...

True, but Jonah posted from Nassau, and I'm assuming he is in the Bahamas, not in NY.