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Old 05 March 2021, 16:26   #1
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Help me chooose! Yamaha 70hp or 75 for a 485 rib

Hi guys!!

(Sorry for my english)

I am to purchase a Brig Navigator 485, rated for 75HP

I want to put the Yam 75 on it but some people and my dealer told me the added weight of the engine will not enhance the performance so much.

The 75HP is double the displacement of the 70Hp. Some people who had the chance to try both engine on their fishing boat say the 75HP is alot better performance wise. But its fishing boat, maybe its different for a RIB??

My friend got a Bayrunner 500 last year with a 70hp and i was not fully impressed by the hole shot and the Brig is heavier than the Bayrunner

Any helpful hint on this?? Maybe in the 1.8 liter, the difference is bigger if you choose the 90 hp, not so much the 75??
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Old 05 March 2021, 16:54   #2
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Originally Posted by fortress66 View Post
Hi guys!!

(Sorry for my english)

I am to purchase a Brig Navigator 485, rated for 75HP

I want to put the Yam 75 on it but some people and my dealer told me the added weight of the engine will not enhance the performance so much.

The 75HP is double the displacement of the 70Hp. Some people who had the chance to try both engine on their fishing boat say the 75HP is alot better performance wise. But its fishing boat, maybe its different for a RIB??

My friend got a Bayrunner 500 last year with a 70hp and i was not fully impressed by the hole shot and the Brig is heavier than the Bayrunner

Any helpful hint on this?? Maybe in the 1.8 liter, the difference is bigger if you choose the 90 hp, not so much the 75??


1st rule of outboards ďthere is no replacement for displacementĒ
Donít get seduced by HP, torque is your friend.
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Old 05 March 2021, 16:59   #3
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hi!!

Torque?? how i should know of this?? IM a beginner!!

According to Yamaha performance charts:

Alumacraft Voyageur 175 75HP 2075 lbs

4500RPM 27.7 MPH

Alumacraft 175 70HP 1994lbs

4500RPM 22.4 MPH


The 75 seems to do a better job no??
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Old 05 March 2021, 17:13   #4
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Originally Posted by fortress66 View Post
hi!!



Torque?? how i should know of this?? IM a beginner!!



According to Yamaha performance charts:



Alumacraft Voyageur 175 75HP 2075 lbs



4500RPM 27.7 MPH



Alumacraft 175 70HP 1994lbs



4500RPM 22.4 MPH





The 75 seems to do a better job no??


Torque = Couple moteur. 75cv plus couple dí70cv.
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Old 05 March 2021, 17:15   #5
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Originally Posted by Pikey Dave View Post
Torque = Couple moteur. 75cv plus couple dí70cv.


So in clear, Go with the 75???

OK any drawback on this?? I mean, having more weight on the transom for a RIB boat.. Handling probleme at higher speed?? BOW always up in the air?? Stuff like that. 75HP is 100lbs heavier

I just want to make sure i make the right choice
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Old 05 March 2021, 17:30   #6
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Originally Posted by fortress66 View Post
So in clear, Go with the 75???



OK any drawback on this?? I mean, having more weight on the transom for a RIB boat.. Handling probleme at higher speed?? BOW always up in the air?? Stuff like that. 75HP is 100lbs heavier



I just want to make sure i make the right choice


If you have more weight forward, battery/fuel/helm etc. To balance the extra weight of the 75hp engine, I would go with the 75. The extra torque will compensate for the weight.
All IMO naturally
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Old 05 March 2021, 17:33   #7
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Originally Posted by Pikey Dave View Post
If you have more weight forward, battery/fuel/helm etc. To balance the extra weight of the 75hp engine, I would go with the 75. The extra torque will compensate for the weight.
All IMO naturally
i cannot really do this with the navigator. But the NAV got his fuel tank in the HULL, middle boat

thx for your help
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