Advice Required

hooked · 06 December 2007, 20:16

Hi, I bought a RIB 6.20 meters custom made . I am planning to buy a Honda outboard 90 Hp or 130 Hp ? ( there is no 115 Hp in our country ).
Now, I need a figure if I put 90 Hp ( 4 stroke ) what will be the speed and same for 130 Hp?
The inflatable parts of RIB is a bit bigger ( wider ) than normal 6.2 meter RIBS.
So, I will be very happy if you give me approx. speed values.
Thanks alot,
Arif

Nos4r2 · 06 December 2007, 21:58

You can't really tell speed just by the engine as a lot depends on the weight and type of hull. However, I personally wouldn't put a 90hp on a 6.2m boat. It'll probably be underpowered unless it's an exceptionally light boat.

kingfisher69 · 06 December 2007, 22:30

Quote:

Originally Posted by Nos4r2

You can't really tell speed just by the engine as a lot depends on the weight and type of hull. However, I personally wouldn't put a 90hp on a 6.2m boat. It'll probably be underpowered unless it's an exceptionally light boat.

Hi Arif As Nos correctly states the weight of the boat is a major factor but also the difference in weight of the power head on a 4 stroke is significantly greater, so a technical calculation based on the weight of the boat and output of the engine and the engines power to weight ratio is the only way to calculate accurately. Your other alternative is to consider a 2 stroke motor around the 110 + region which has a much better power to weight ratio. hope that makes some sense Regards Gary

hooked · 08 December 2007, 16:49

Quote:

Originally Posted by kingfisher69

Hi Arif As Nos correctly states the weight of the boat is a major factor but also the difference in weight of the power head on a 4 stroke is significantly greater, so a technical calculation based on the weight of the boat and output of the engine and the engines power to weight ratio is the only way to calculate accurately. Your other alternative is to consider a 2 stroke motor around the 110 + region which has a much better power to weight ratio. hope that makes some sense Regards Gary

Hi Gary,
Thanks for your reply but in our part of the world gas is very expensive it is about 2 euros per liter ( 1.88 E ) so , we mainly us ethis boat to fish tuna in aegean heavy seas and we have to know real figures of 2 stroke or 4 stroke fuel consumption charts. Do you know any realistic informations or web pages..Thanks alot ARIF

hooked · 08 December 2007, 16:51

Quote:

Originally Posted by Nos4r2

You can't really tell speed just by the engine as a lot depends on the weight and type of hull. However, I personally wouldn't put a 90hp on a 6.2m boat. It'll probably be underpowered unless it's an exceptionally light boat.

Thanks , boat weight is 500 kgs. without engine...
So, what do you recommend ? 130 HP is better ??
Thanks alot,
Arif

MarkM · 08 December 2007, 17:08

Hi Arif,
I had a Honda 90 on a Wiking Wega RIB of about 5 m which is a quit heavy boat. Had a speed of 63 km/hr.
Go for the 130 hp. A 90 uses to much gas as it has to work to hard in your situation.

walruz · 08 December 2007, 22:19

Hi

Congrats on the big boat. I have a 90 2 stroke on my 5.4. You DEFINITELY want to go with the bigger 4 stroke. a 90 on your boat will have to work at teh top end of its' throttle and so will be very thirsty. A 130 working in middle revs will probably use the same or less as a 90 thrashing itself.

Walruz

PS I get 36.5 kts from my 90

MarkM · 09 December 2007, 07:57

P.S. get the new version of the 130, does not use as much fuel as the older type 130 and has got more power.