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Author Topic:   Bigfoot Lower End

Garrett posted 07-30-2011 01:29 PM ET (US)
Usually, when people ask what a Bigfoot lower end means in terms of performance, they get the 'Bigfoot motors are designed for displacement boats and work boats' quote...which really isn't an answer. So let's see if we can make the difference clearer for prospective buyers.
Here is my question, on the same boat with a comparable prop type/pitch, what are the performance advantages between a Bigfoot motor and a normal lower case motor?
As I understand it (and from experience)=
Bigfoot advantages:
-quicker/easier hole shot
-better pulling power (waterskiing and such)
-better cornering (less ventilating because prop is deeper)

Normal Lower End advantages:
-about 1 mph speed increase
-about 3% fuel efficiency increase (less drag)
-3" less deep in water = less chance of hitting something.
*IF you are pulling waterskiers or are starting/stopping often and need to jump out of the hole a lot = the Bigfoot is probably more fuel efficient. This is because getting out of the hole takes up more fuel if your boat is struggling.

Everyone agree on the above?

Garrett posted 07-30-2011 01:32 PM ET (US)
Oh, just so we are clear, the above is in reference to a planing type hull....let's assume a Shallow V hull on a 1000lbs boat.
number9 posted 07-30-2011 07:27 PM ET (US)

quote:
let's assume a Shallow V hull on a 1000lbs boat
My Outrage with a Yamaha T50 falls into that category. Easy/quick to plane and 28mph at WOT. Would want to try a normal F50. I'm a High Thrust fan.
Garrett posted 07-30-2011 08:12 PM ET (US)
With my 60hp Bigfoot, I get 35mph at WOT...but I also have a 14pitch Vengeance (stainless) prop on my setup.
So, do you agree with the above Bigfoot vs 'normal foot' advantages in relation to each other?
Tohsgib posted 07-31-2011 10:52 AM ET (US)
I would like to see how it is 3" shorter.
number9 posted 08-01-2011 05:22 AM ET (US)
Maybe in the 1" shorter range.
Garett, can't agree with the above Bigfoot vs 'normal foot' advantages in relation to each other you state. There are no disadvantages on my Outrage. The normal gear case would be slower and use more fuel IMO.
sosmerc posted 08-02-2011 12:54 AM ET (US)
Let me start by saying I DO NOT have the figures to back up what I am about to say.....but here goes.
With regards to a "bigfoot" vs standard gearcase on let's say a Merc F60 on a 15 Sport Whaler:
The larger diameter prop as well as the much larger anti-ventilation plate as well as the overall gearcase design of the bigfoot will enable the engine to be mounted much higher on the transom for less drag, less spray and better handling. The greater gear reduction and larger prop will improve low end torque for better hole-shot and the engine will keep the boat on plane at a lower rpm.
With the proper setup, my guess is the bigfoot equipped boat should be at least as fast, if not faster. The bigfoot gearcase is also more durable. Brunswick certainly made the right choice when they made the bigfoot F60 the "standard" factory setup on the new Sport 15.
number9 posted 08-02-2011 11:10 AM ET (US)
sosmerc,
Excellent information and may help dispel many of the negatives many associate with using a bigfoot as a direct replacement for a regular gearcase motor.
Hopefully the marketing guys don't start pushing them and increase the demand/price.

Salmon Tub posted 08-04-2011 05:04 PM ET (US)
It is about 3" shorter. With the smaller diameter gearbox and smaller prop (10"-11" rather than the 12"-14" diameter prop) you loose +/-1.5 inches since the center of the prop shaft is that much closer to the cavitation plate on the standard leg. If you measure the distance from the plate to the tip of the skeg you do get about 3" less.
number9 posted 08-05-2011 12:33 AM ET (US)

quote:
It is about 3" shorter. With the smaller diameter gearbox and smaller prop (10"-11" rather than the 12"-14" diameter prop) you loose +/-1.5 inches since the center of the prop shaft is that much closer to the cavitation plate on the standard leg. If you measure the distance from the plate to the tip of the skeg you do get about 3" less.

Thanks for posting this. It prompted me to recheck my info for differences of Yamaha F50 and T50. My earlier info was in error. My mind has been conditioned here to think shaft length and ignore most other dimensions. I don't have the Bigfoot info.
Amount of dimension that T is greater than F, from Yamaha Service Manual:
Shaft length -- 0.1"
AV plate-p shaft ctr. -- 0.6"
P shaft ctr-skeg -- 0.9"
Transom-skeg -- 1.6"
According to the manual you can add up to 1.1" depending upon trim.
Garrett posted 08-12-2011 01:24 PM ET (US)
I am sure that the depth difference between the normal lower end and the BigFoot lower is more like 3 inches (if mounted identically).

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Author	Topic: Bigfoot Lower End
Garrett	posted 07-30-2011 01:29 PM ET (US) Usually, when people ask what a Bigfoot lower end means in terms of performance, they get the 'Bigfoot motors are designed for displacement boats and work boats' quote...which really isn't an answer. So let's see if we can make the difference clearer for prospective buyers. Here is my question, on the same boat with a comparable prop type/pitch, what are the performance advantages between a Bigfoot motor and a normal lower case motor? As I understand it (and from experience)= Bigfoot advantages: -quicker/easier hole shot -better pulling power (waterskiing and such) -better cornering (less ventilating because prop is deeper) Normal Lower End advantages: -about 1 mph speed increase -about 3% fuel efficiency increase (less drag) -3" less deep in water = less chance of hitting something. *IF you are pulling waterskiers or are starting/stopping often and need to jump out of the hole a lot = the Bigfoot is probably more fuel efficient. This is because getting out of the hole takes up more fuel if your boat is struggling. Everyone agree on the above?
Garrett	posted 07-30-2011 01:32 PM ET (US) Oh, just so we are clear, the above is in reference to a planing type hull....let's assume a Shallow V hull on a 1000lbs boat.
number9	posted 07-30-2011 07:27 PM ET (US) quote: let's assume a Shallow V hull on a 1000lbs boat My Outrage with a Yamaha T50 falls into that category. Easy/quick to plane and 28mph at WOT. Would want to try a normal F50. I'm a High Thrust fan.
Garrett	posted 07-30-2011 08:12 PM ET (US) With my 60hp Bigfoot, I get 35mph at WOT...but I also have a 14pitch Vengeance (stainless) prop on my setup. So, do you agree with the above Bigfoot vs 'normal foot' advantages in relation to each other?
Tohsgib	posted 07-31-2011 10:52 AM ET (US) I would like to see how it is 3" shorter.
number9	posted 08-01-2011 05:22 AM ET (US) Maybe in the 1" shorter range. Garett, can't agree with the above Bigfoot vs 'normal foot' advantages in relation to each other you state. There are no disadvantages on my Outrage. The normal gear case would be slower and use more fuel IMO.
sosmerc	posted 08-02-2011 12:54 AM ET (US) Let me start by saying I DO NOT have the figures to back up what I am about to say.....but here goes. With regards to a "bigfoot" vs standard gearcase on let's say a Merc F60 on a 15 Sport Whaler: The larger diameter prop as well as the much larger anti-ventilation plate as well as the overall gearcase design of the bigfoot will enable the engine to be mounted much higher on the transom for less drag, less spray and better handling. The greater gear reduction and larger prop will improve low end torque for better hole-shot and the engine will keep the boat on plane at a lower rpm. With the proper setup, my guess is the bigfoot equipped boat should be at least as fast, if not faster. The bigfoot gearcase is also more durable. Brunswick certainly made the right choice when they made the bigfoot F60 the "standard" factory setup on the new Sport 15.
number9	posted 08-02-2011 11:10 AM ET (US) sosmerc, Excellent information and may help dispel many of the negatives many associate with using a bigfoot as a direct replacement for a regular gearcase motor. Hopefully the marketing guys don't start pushing them and increase the demand/price.
Salmon Tub	posted 08-04-2011 05:04 PM ET (US) It is about 3" shorter. With the smaller diameter gearbox and smaller prop (10"-11" rather than the 12"-14" diameter prop) you loose +/-1.5 inches since the center of the prop shaft is that much closer to the cavitation plate on the standard leg. If you measure the distance from the plate to the tip of the skeg you do get about 3" less.
number9	posted 08-05-2011 12:33 AM ET (US) quote: It is about 3" shorter. With the smaller diameter gearbox and smaller prop (10"-11" rather than the 12"-14" diameter prop) you loose +/-1.5 inches since the center of the prop shaft is that much closer to the cavitation plate on the standard leg. If you measure the distance from the plate to the tip of the skeg you do get about 3" less. Thanks for posting this. It prompted me to recheck my info for differences of Yamaha F50 and T50. My earlier info was in error. My mind has been conditioned here to think shaft length and ignore most other dimensions. I don't have the Bigfoot info. Amount of dimension that T is greater than F, from Yamaha Service Manual: Shaft length -- 0.1" AV plate-p shaft ctr. -- 0.6" P shaft ctr-skeg -- 0.9" Transom-skeg -- 1.6" According to the manual you can add up to 1.1" depending upon trim.
Garrett	posted 08-12-2011 01:24 PM ET (US) I am sure that the depth difference between the normal lower end and the BigFoot lower is more like 3 inches (if mounted identically).