Rustnrot's New Boat Engines
05-26-2005, 07:40 PM
#11
Administrator
Join Date: Jul 2001
Location: Stuart, FL
Posts: 24,416
A lot of the rotary advantage would be high RPM's. Which isnt all that helpful in a boat application. I mean you can only spin the prop so fast, then it cavitates and is useless. I know pettit has a rotary powered boat as well.
05-30-2005, 04:58 PM
#14
Senior Member
Join Date: Nov 2003
Location: Ireland
Posts: 907
[quote name='GLC13B' date='May 30 2005, 04:04 AM']Hull displacement has alot to do with torque issue's ! There are three basic type of hull and they're effect by what's driving them.
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Does the shape of the hull have any effect on torque requirements? My impression was that boats didn't need gobs of torque but now that I think about it, it makes sense.
Mark
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Does the shape of the hull have any effect on torque requirements? My impression was that boats didn't need gobs of torque but now that I think about it, it makes sense.
Mark
05-30-2005, 08:19 PM
#15
Super Moderator
Join Date: Feb 2002
Location: Amityville, New York
Posts: 12,288
[quote name='inanimate_object' date='May 30 2005, 05:58 PM']Does the shape of the hull have any effect on torque requirements? My impression was that boats didn't need gobs of torque but now that I think about it, it makes sense.
Mark
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you ever try to run your hand flat in the water? its hard, but if you knife the water its alot easier-
just like when you hold your hand out the window- you can think of it the same as aerodynamics.
Mark
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you ever try to run your hand flat in the water? its hard, but if you knife the water its alot easier-
just like when you hold your hand out the window- you can think of it the same as aerodynamics.
05-31-2005, 04:01 AM
#16
Senior Member
Join Date: Nov 2003
Location: Ireland
Posts: 907
[quote name='Rob x-7' date='May 31 2005, 02:19 AM']you ever try to run your hand flat in the water? its hard, but if you knife the water its alot easier-
just like when you hold your hand out the window- you can think of it the same as aerodynamics.
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Ok, but what's getting me is a boat weighing x kilo's is always going to displace x volume of water regardless of hull shape -how much of a difference do 2 different hull designs experience considering this?
Mark
just like when you hold your hand out the window- you can think of it the same as aerodynamics.
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Ok, but what's getting me is a boat weighing x kilo's is always going to displace x volume of water regardless of hull shape -how much of a difference do 2 different hull designs experience considering this?
Mark
10-14-2005, 10:24 PM
#20
Junior Member
Join Date: Oct 2005
Posts: 4
Have a Fichtel and Sachs rotary in my 6500 lb. 28' Ranger 28,which would be a displacement hull,doesn't have any problem pushing her along at displacement speed.Picture of the Ranger 28 Candyman crossing the Straits of Juan de Fuca,uses about a half gallon an hour.