flatbottoms vs runnerbottoms

[Bob Hostetter]

It seems to be the accepted wisdom that flatbottoms are faster and more stable in choppy water then runnerbottoms. It also seems to be agreed upon that runnerbottoms are faster in smooth water. I think I understand why runner's are faster, less wetted surface.
Why are flatbottoms such as the "B" boats better in rougher water? Better fro/aft balance point, different entry profile on the keel line, larger contact surface at the transom, narrower/wider transom?
Why couldn't you set up a runnerbottom to handle the rougher water?

[BILLY.B]

It seems to be the accepted wisdom that flatbottoms are faster and more stable in choppy water then runnerbottoms. It also seems to be agreed upon that runnerbottoms are faster in smooth water. I think I understand why runner's are faster, less wetted surface.
Why are flatbottoms such as the "B" boats better in rougher water? Better fro/aft balance point, different entry profile on the keel line, larger contact surface at the transom, narrower/wider transom?
Why couldn't you set up a runnerbottom to handle the rougher water?Can't see why some of the more knowledgeable guru's haven't stepped up to help you out on this. Trying to make a drag boat into a circle boat would be quite a feat. The "B" boats as they are referred to are definitly better for the rough water as they do have a deeper entry (keel) to help break up the water plus they don't ride on a pocket of air under the hull like a runner bottom does which is caused by dropped chines and a center pad. A runner bottom is actually wider at the transom then a "B" boat and a Bezer is even narrower yet. A drag boat has barely any center fin hanging down (maybe 3 to 3 1/2") and a "B" has two connected that are anywhere between 6" to 7" in depth that help it turn. The rudders are different also. A "B" boat has 2 and sometimes 4 strakes to help the "B" boat handle, and there are somethings you can do to help improve the bottom of a "B" boat but there are quite a bit of limitations to how far you can take it per the APBA rule book. Unless your Gordy (the real K boat King) then you can do whatever you have to too win :rollside: .

[GofastRacer]

Well you beat me to it, LOL that about explains it!..

[uclahater]

Can't see why some of the more knowledgeable guru's haven't stepped up to help you out on this. Trying to make a drag boat into a circle boat would be quite a feat. The "B" boats as they are referred to are definitly better for the rough water as they do have a deeper entry (keel) to help break up the water plus they don't ride on a pocket of air under the hull like a runner bottom does which is caused by dropped chines and a center pad. A runner bottom is actually wider at the transom then a "B" boat and a Bezer is even narrower yet. A drag boat has barely any center fin hanging down (maybe 3 to 3 1/2") and a "B" has two connected that are anywhere between 6" to 7" in depth that help it turn. The rudders are different also. A "B" boat has 2 and sometimes 4 strakes to help the "B" boat handle, and there are somethings you can do to help improve the bottom of a "B" boat but there are quite a bit of limitations to how far you can take it per the APBA rule book. Unless your Gordy (the real K boat King) then you can do whatever you have to win :rollside: .
How many shots can Gordy take in one day without a response :idea: OUCH :boxingguy

[olbiezer]

wheres the king??????

[Bob Hostetter]

Billy B,
The turning fins I understand add directional stability and provide a more solid pivot point for turning. The strake's provide additional directional stability and the rudder aids in turning and maybe some directional stability.
The outer chimes on a runnerbottom, especially with combined with the runner's reduced riding surface, would effect the turning ability. Falling off the center runner and at the same time having the chime hook can cause a rather violent turning motion. But as far as I can tell most of these things would effect the boats ability to turn at high speeds and not necesarially effect the boats ability to handle chop in a straight line.
Would changing to a deeper, possibly double fin and a circle boat style rudder allow the runner to handle chop like circle boat? If it would then it seems to me that you could setup a runnerbottom (maybe layed up without the outer chimes) to run faster as a circle boat in the chop. Even without the outer chimes you would still have a smaller wetted surface at speed and without the chimes much more predictable turning.
The reason for all the questions is I am planning on building a flat this winter and haven't run one since 1985 when I switched over to a 20 foot deep 'v' Hallett vdrive. But now the kids are grown up and its time to play again.....
By the way, you painted my last flat (actually a Canyon Marine Runnerbottom) in the early 80's. Are your prices still the same? Just kidding......
Thanks for your help,