Weight alone doesn't create drag at low speed. Only indirectly through wetted surface area
A longer hull will also increase the wetted surface area. Because the ideal shape if low wetted surface is the only target, is a half sphere. But that wouldn't be a fast sailboat for other reasons.
This 26m/85 feet foiler was built 1984 with a target weight of 11 tonnes, which ended up being 16.5 - 18 tonnes according to different sources.
The 24m/80 foot Harryproa Ferry, has a target weight of 7 tonnes (or 5 stripped out for racing). Less than half the weight of the tri built in 1984, maybe less than a third it comes out width the same weight as the target.
Half the weight should mean less surface area. But then the old foiler has more than twice the upwind sail area (340m2 vs 155m2), and 5 times the sail area downwind (790m2).
>Can not the HP carry a larger sail, compared to the tri, assuming similar margins of safety?
Probably, because the foiler has beam of 12.5m on each side, with a 31m mast. The Ferry is 9m wide, with 22m masts. I don't think these boats compare good though, because they are designed with completely different criterias. The Ferry is not an all out racer, which the foiler was, and which Bucketlist was. The Ferry probably has limited width to be able to fit in some harbours. And not the most extreme sailarea to be safe even in strong winds. I think its a very nice concept for it's intended purpose.
>Or is wetted surface the larger variable?
At low speed the ratio of sailarea to wetted surface area should be the ratio of interest.
But I also think this requires an in depth analysis.
Can not the HP carry a larger sail, compared to the tri, assuming similar margins of safety?
Is not the hp in this comparison assumed lighter than the tri?
Would not larger sail and lighter weight favour the HP in light airs?
Or is wetted surface the larger variable?
On March 2, 2019 10:35:57 PM UTC, "Rick Willoughby rickwill@bigpond.net.au [harryproa]" <harryproa@yahoogroups.com.au> wrote:
| The difference in wetted surface between proa and tri will not be 40%
| in light conditions but something less than that. There needs to be
| a reasonable immersed length of the ama to avoid wave making drag.
|
| Then the tri has the windage of the windward ama and its beams. That
| is not insignificant.
|
| The light air performance is likely to favour the tri but it would
| require detailed analysis to assess the difference.
|
|
| Rick