3R not (only) design's questions

Had a few questions concerning the 3R’s and other designs…

My 3R that i am building is 46 inch long and just over 6 inch wide.
Cougar

What makes you chose a certain lenght and or wide? I mean why 46 inches and not 40…sure in theory, longer is faster

Hull Speed = 1.34 * (LWL)1/2

[SIZE=2]from sailing USA

[/SIZE]…but is that all?

sorry to bother with noobies design questions…but was wondering…winter already here:cat:

Wis,

From what I have read on the forum lately, I think some people might not completely understand how the 3R class rule works. I think some people might be confused about the difference between lwl and loa.

loa = the distance from the tip of the bow, to the aft most point on the transom.

Lwl = the distance from the point the bow enters the water to the point the transom leaves the water.

For example my boat is 45 inches loa, but only 35 inches lwl.

The 3r rule is ?3<=LWL*SA/ 7000 ? thus longer lwl yields less sail area.

The trick is that as a hull heels, the ?working? lwl increases. For example when I get my hull heeled I can have a ?working? lwl of 42 or 43 inches (significantly greater than my rated lwl).

Now as to the question of why this or why that, a lot depends on the designers opinion, and has no simple answer.

Does that answer your question?

so it all depends on the designer’s and his “sorcery”…and maybe his
“conditions” ??!!

thanks for the tip…

:darth: As with all "RATING’ type design rules the trade off is waterline length against sail area. :devil3:

The first question a designer should ask is “do I sail in a soft, medium or hard wind strength most of the time”.
The answer will indicate the type of design most suitable for his venue “most of the time”.
So a heavy wind 3R could be 45" lwl, with 466sq" SA,
Medium 40" lwl, with 525 sq"
Light wind 35" lwl, with 600 sq"

Other extreams could be 30" lwl - 700" or 50’ lwl - 420". :idea:

It is no use having to fly your number two rig most of the days you sail because your craft is over canvassed. Better to trade off for waterline length, for, as WIS correctly points out, “longer equals faster”. :long:

wis
The reason i went to a 46 inch long hull was to have OVERHANGS. Now i know this may sound stupid. but I wanted a long waterline, but not alot of hull n the water. so i went with a 35 inch waterline. but that is only with the hull sitting still. when the boat is moving. the hull will heel. right? then i can use alittle more at the bow and stern. maybe get a 42 inch waterline. without adding anything to the hull. like ian said . the trade off is sail area. I will only be able to carry 600 sqr inchs. I will be using my old set of seawind sails. IN fact I will be using a seawind rig. Dan and I had chatted a few times, and we both love the americas cup. and I wanted a 3r that had the same look as a iacc boat.
but if I am wrong. i can always stop building it
cougar

wis
The reason i went to a 46 inch long hull was to have OVERHANGS. Now i know this may sound stupid. but I wanted a long waterline, but not alot of hull n the water. so i went with a 35 inch waterline. but that is only with the hull sitting still. when the boat is moving. the hull will heel. right? then i can use alittle more at the bow and stern. maybe get a 42 inch waterline. without adding anything to the hull. like ian said . the trade off is sail area. I will only be able to carry 600 sqr inchs. I will be using my old set of seawind sails. IN fact I will be using a seawind rig. Dan and I had chatted a few times, and we both love the americas cup. and I wanted a 3r that had the same look as a iacc boat.
but if I am wrong. i can always stop building it
cougar