Note the line of waves and the change in angle where there was a current differential.
............. You've posted so many pics I have the feeling you can't make a post without putting up some kind of picture. ............
Well, they say a picture is worth a thousand words (a "kiloword") so think of all the typing he saves. Not to mention bandwidth.
It might be worth reviewing your math ... a thousand words is about 16KB, one of Mark's pics is close to 200KB.
It might be worth the bandwidth if it were in context but a picture of a bergy bit taken from a cruise ship in some unknown location in a thread by and about a member's photos of his voyage south seems like a bit too much "me too" for good taste.
Last time it was posted the reason was water depth.
"but going one way into it is often compensated for by going with it at some point."
To me the question is to what extent.
I don't see how bucking wind and then going w it could work out to be a plus. But if there was no current and the wind was the same going both ways at the same speed it would seem to average out. If one went the same speed the resistance of the boat would remain the same below the WL. The wind would have the same difference going both ways would it not? Take away 2 eggs .. give back 2 eggs. Something tells me it can't be so though. Don't know what the something is though. I think in reality it has to do w something being not linear. Like the headwind would increase the drag more than the tailwind would reduce it????
Daddyo,
Lets see a good pic of your aft end. Perhaps I'm wrong but every DeFever I've seen is semi-disp without a doubt but there was a smaller (34' ?) DeFever that surprised me re her lines aft. A Krogen 42 has almost no submerged transom and is clearly a full disp boat. I'd rather not go into the Buttock Line stuff as some here don't like it but it is the best way to define a full disp hull in the aft end. Let's see what you've got.
Daddyo,
Yes now that I can see your QBBL fairly well and your emersed transom. The DeFever is definitely semi disp and a bit closer to full disp than an Island Gypsy that I think (hull shape wise) is on the other side of SD. As is many to most other trawlers on the forum.
I see on the top pic the chine is straight (or parallel to the WL) as would be the case w a full plaining hull at rest. With the DF your inner buttock line (where bottom meets the keel) has a rather steep angle for trawlers. So your boat is a semi-disp and a bit closer to FD.
For years I've seen the submerged straight chine aft and in my own mind labeled the DF a SD boat. But quite a few guys obviously haven't liked that so I'm glad you pulled that out in the open. The DF is closer to FD.
Here is a full blown full disp hull. You can see that the QBBL running fore and aft half way between the keel and the side of the boat is very steep. Could be about 30 degrees.
A box is full displacement...ask any tugboat captain..How about hard chine full displacement