Straight hulls vs round hulls

When I was browsing the plans to decide which RG65 boat to build, I saw many that are more rounded lengthwise (strip built, round chine) and a few that are more straight (paneled, hard-chine) and wondered what the difference would be when sailing.

IMO, the hard-chined RG65 hulls have less buoyancy in the bow because of the hull’s slender shape, and I think something like that would be better in light air/calm water with less ballast, while the rounder hulls have more displacement just about everywhere and could take on bigger surf as well as more ballast in the keel.

Obviously boat designs are successful for sailing and have success in competition, but I’m interested if the hull shape has any effect on the sailing. From the USOM class, the thin hulls generally win more often.


I’ll probably build the rounder boat the next time. I chose the Minitux II for the simplicity of the build.

Also something to think about is wide vs narrow.


The round hulls look pretty wide to me, and the straight ones are narrow. I haven’t seen one that was really wide yet. What would you consider to be “wide?” Minitux II is 125mm.

Here are some specs from different rgs. All the beams are in MM.

What did you draw from the specs? the beams ranged from 100 - 160 mm

Wouldn’t that be the width of the hulls or am I confused ?

One other thing to look at is the waterline beam. On the Scharming I sailed, wl beam is 85mm, while on deck it is 118. The blue dragon is 120 and wl beam is 116. So it has a lot less flare.

Nope - you are correct - beam is “width” and noted on the list - either maximum beam (probably at deck) and maximum beam at waterline.
I have no idea what TomoHawk is asking.


Bouyancy in the bow is not a matter of round vs. chine…it’s the relative areas fore and aft that controls that. My chine hulls have close to equal volumes fore and aft.

Similarly, displacement is not a matter of round vs. chine or narrow vs. wide.

Traditionally, chine hulls have been considered less efficient going upwind, because the chine creates more drag as the boat slips a bit sideways, as they always do. In real conditions, we haven’t seen a definitive difference in either Footys or RG65s. I think a lot of other factors have greater influence over boat speed and handling.


Newer designs in all categories, from IOM to large oceanic sailboats have incorporated chine sections near the stern. Apparently the best combination is a round hull in the bow and chine in the last third of the length.