Tracking vs. Sideslip

This is what I’ve noticed on several occasions. I usually paddle very hard chine hulls and when paddling with softer chine boats at times they seem to slide downwind from me especially in a quartering headwind. Now as a sailor I can make a case of the chines acting like a keel or centerboard and holding a course better.

Question is has anyone else noticed this…

keel line or bottom form
I’ve found that the shape of the bottom of the boat or the keel seems to make a significant difference in the boats resistance to sideslipping.

For example, I found the hard chined but round hulled Ellesmere to be more prone to side slipping (or crabbing) than my soft chined but slightly vee hulled Aquanaut.

how pronounced the keel makes the most difference. However, if you’re compensating somewhat for a beam wind (without the skeg down) by edging a bit, then the chine shape can affect whether the boat side slips a bit.


lateral resistance
I’d wager rocker plays a big part too.

A tale of two boats
I’ve experienced noticeable side slip in only two boats, the Dagger Meridian and Nick Schade’s Night Heron. The only similarities I can see between the two boats is that they are relatively flat bottomed in the center, with rounded chines and have a fair amount of rocker.

Amount of boat above water
The amount of boat (and gear and you) above water acting as a sail area should be the primary factor, then the depth of keep or chine and how long those extent toward the ends (displacement and distribution of it).

Simple ratio of sail area to “sea anchor area” should explain the dominant forces, with the other more minor hull design variations contributing to your subjective feel of what’s going on.

If it were possible to measure the volume above water and compare to displaced volume (and block coefficient) you could pretty easily come up with a “crabbing factor” to compare boats.

No one wants numbers for bad things though! People who really have/notice issues with it tend to already be more interested in longer narrower hulls that are less effected.

Could be worse GH - you could paddle canoes!

No Problem…
With my pointA to pointB boats. I quess the most noticeable has been on a long straight run with an Avocet next to me.