Why move crew to the bow going down wind?

I raced with a buddy today on his Catalina 22. During the down wind running wing and wing all of the other boats were sending crew forward to lift the stearn out of the water. Why? I have been racing for 15 years and have not seen this before.

Cliff

 

Because of the strong bilged and wider shape aft on a modern light displacement hull, there is more wetted surface for a given displacement sitting the lines low aft than there is if the bow is deeper and the stern up on the lines. Normally it is only done in light winds when the sail does not have enough force to require the crew aft to keep the bow up. I've known about it since I started racing in the late 70's, when it was a common racing tactic.

 

The transom of my little tub is about 6" above the water when it is sitting at the dock. I can stand at the transom and still not wet it. But once it's underway, with 2 or 3 crew in the cockpit, the transom is always 2 - 3" under water (under the stern wave). It gurgles and drags. I have seen the speed increase on the gps by moving crew forward.

I have considered mounting a convex ski-boat mirror over the trasom so that I could tell at a glance if the water flow was smooth or disturbed.

 

That's an interesting idea.

 

Piper,

Don't worry about seeing, just listen.

Moving weight around: Yes, weight on the bow will reduce the wetted area of many boats, but, it also reduces waterline length. Conclusion: Rely more on empirical data than theorizing.

Yoke.

 

Always rely on empirical data to support or refute any theory!

For light weight, flattish bottomed boats, move crew weight forward in light air to raise the stern out of the water and minimize wetted surface area; move crew weight aft in planing conditions to raise the bow out of the water and minimize wetted surface area. And inbetween? See rule #1!