Shorter drives?
01-24-2006, 03:44 PM
#31
Platinum Member
Platinum Member
Re: Shorter drives?
Kamma,
My Scarab does not have a notch. Straight Vee. I did not check the speeds at cruise. My guess is the cruise was up due the the Bravo 1 vs. the Mirage props.
My Scarab does not have a notch. Straight Vee. I did not check the speeds at cruise. My guess is the cruise was up due the the Bravo 1 vs. the Mirage props.
01-25-2006, 12:30 PM
#33
Platinum Member
Platinum Member
Re: Shorter drives?
Kaama,
At the end of the project, the engines were 505 ci @ 780 HP naturally aspirated. The top speed was 105 mph with Bravo I's 28p turning in (103 mph out) @ 6600 rpm. Add +2 mph to both with Herring 5-blades at the same 28p (Herrings - 200 rpm vs B-1's) I might have had slightly more MPH opportunity if I had Herring 27p to test with. At 9500 lbs. with 20-40 gal of fuel an two on board, this is a "hull efficiency" of 250...not bad for a 1987 straight vee.
At the end of the project, the engines were 505 ci @ 780 HP naturally aspirated. The top speed was 105 mph with Bravo I's 28p turning in (103 mph out) @ 6600 rpm. Add +2 mph to both with Herring 5-blades at the same 28p (Herrings - 200 rpm vs B-1's) I might have had slightly more MPH opportunity if I had Herring 27p to test with. At 9500 lbs. with 20-40 gal of fuel an two on board, this is a "hull efficiency" of 250...not bad for a 1987 straight vee.
01-25-2006, 12:56 PM
#34
VIP Member
VIP Member
Re: Shorter drives?
Originally Posted by BenPerfected
Kaama,
At the end of the project, the engines were 505 ci @ 780 HP naturally aspirated. The top speed was 105 mph with Bravo I's 28p turning in (103 mph out) @ 6600 rpm. Add +2 mph to both with Herring 5-blades at the same 28p (Herrings - 200 rpm vs B-1's) I might have had slightly more MPH opportunity if I had Herring 27p to test with. At 9500 lbs. with 20-40 gal of fuel an two on board, this is a "hull efficiency" of 250...not bad for a 1987 straight vee.
At the end of the project, the engines were 505 ci @ 780 HP naturally aspirated. The top speed was 105 mph with Bravo I's 28p turning in (103 mph out) @ 6600 rpm. Add +2 mph to both with Herring 5-blades at the same 28p (Herrings - 200 rpm vs B-1's) I might have had slightly more MPH opportunity if I had Herring 27p to test with. At 9500 lbs. with 20-40 gal of fuel an two on board, this is a "hull efficiency" of 250...not bad for a 1987 straight vee.
in or out ?
01-25-2006, 04:12 PM
#35
Re: Shorter drives?
BenP,
The reason why I have asked is because your set-up is very close to mine, only I am not running as much HP or RPM's as you. I have a 1990 32' Active Thunder with a conventional "V" hull (non-stepped hull), and no notch in the tansom. The way my drives are set up are with Bravo One XR's on Stellings extention boxes with labbed 32" Bravo One four blades. The drives are stock length cases and they sit about 3.5 to 4 inches (prop shaft centerline) below the hull. I have a pair of IMCO -2" shorties pretty much ready to bolt on. I know that every hull is different, but it would be nice if I could tack on another 5mph as well----but as I have always said; "we shall see".
Anyway, it sounds like you have a very nice running rig. Thanks for your feedback.
The reason why I have asked is because your set-up is very close to mine, only I am not running as much HP or RPM's as you. I have a 1990 32' Active Thunder with a conventional "V" hull (non-stepped hull), and no notch in the tansom. The way my drives are set up are with Bravo One XR's on Stellings extention boxes with labbed 32" Bravo One four blades. The drives are stock length cases and they sit about 3.5 to 4 inches (prop shaft centerline) below the hull. I have a pair of IMCO -2" shorties pretty much ready to bolt on. I know that every hull is different, but it would be nice if I could tack on another 5mph as well----but as I have always said; "we shall see".
Anyway, it sounds like you have a very nice running rig. Thanks for your feedback.
01-29-2006, 03:54 PM
#36
Platinum Member
Platinum Member
Re: Shorter drives?
Kaama,
My set up is also with Stellings extension boxes. Is the last 6-8' of your hull flat? Hook or rocker? This can be important for max top end. What length are your inside strakes in relation to your hulls CG? You may need do some fine tuning in length to get the attitude just right as you trade off some trim leverage with a high X. This is not a big deal... nothing money won't fix!
My set up is also with Stellings extension boxes. Is the last 6-8' of your hull flat? Hook or rocker? This can be important for max top end. What length are your inside strakes in relation to your hulls CG? You may need do some fine tuning in length to get the attitude just right as you trade off some trim leverage with a high X. This is not a big deal... nothing money won't fix!
