Fuel Economy 2006 Yamaha vs 2021 Suziki

[Alex88]

After 15 years of service I have traded in my RIB for a new model.

My previous boat had a 2006 Yamaha F150 on it. The new rib (which is practically the same in terms of weight and dimensions) will have a 2021 Suzuki 175.

Will there be a notable increase in fuel efficiency? has much changed in the 15-year interim? I know they hype up changes in the sales copy but will it amount to much do you think?

I have also opted to coppercoat as she sits on a swing mooring for 3 months in the summer.

[Ferryman]

It should be a bit quieter and a bit more economical. Strictly IMO, they are a bit better but there’s not that much difference.
I would definitely vote for coppercoat, my boat is in the water all year and just needs a lift out in the spring for a power wash - mainly a thin layer of slime.

[Limecc]

We went the other way, from brand new Mercury 40 to fourteen year old Suzuki 50 (albeit very low hours).

Not used it much because of the obvious this past year so no experience of fuel consumption, the boat and engine capacity are bigger anyway. What we did find was the Suzuki engine is much quieter. The Suzuki is four valve per cylinder and fuel injected so the efficiency is always going to be similar to it's newer 'lean burn' counterpart and it has the same California emissions sticker.

Like having EFI instead of carbs, there could be some real gains if there was variable valve timing tech like with some cars (Toyota VVTLI, Honda VTEC) shame we don't see that on outboards. Or maybe it is on some and I overlooked it.

I often look at the JB Mechanical Facebook page to see what outboard remaps he's been doing lately and on the dyno Suzuki generally outperform Yamaha for stock power and also what they can safely get them up to. I think it comes more down to design and differences between brands than it does between newer EFI motors of the same manufacturer. Just my thinking..

P.S. surely prop slip will be the biggest factor in economy/efficiency? Real gains to be had reducing this and getting the right prop. Props have power curves like the engines that drive them.

[Miss Guided]

Dear Mr Alex888

Check this out - https://www.boat-fuel-economy.com/ne...-175-hp-l.html

MGx

[Orwell boy]

Originally Posted by Limecc

We went the other way, from brand new Mercury 40 to fourteen year old Suzuki 50 (albeit very low hours).



Like having EFI instead of carbs, there could be some real gains if there was variable valve timing tech like with some cars (Toyota VVTLI, Honda VTEC) shame we don't see that on outboards. Or maybe it is on some and I overlooked it.
.

Thought it was just me on here living under a rock

[Alex88]

Originally Posted by Limecc

We went the other way, from brand new Mercury 40 to fourteen year old Suzuki 50 (albeit very low hours).

Not used it much because of the obvious this past year so no experience of fuel consumption, the boat and engine capacity are bigger anyway. What we did find was the Suzuki engine is much quieter. The Suzuki is four valve per cylinder and fuel injected so the efficiency is always going to be similar to it's newer 'lean burn' counterpart and it has the same California emissions sticker.

Like having EFI instead of carbs, there could be some real gains if there was variable valve timing tech like with some cars (Toyota VVTLI, Honda VTEC) shame we don't see that on outboards. Or maybe it is on some and I overlooked it.

I often look at the JB Mechanical Facebook page to see what outboard remaps he's been doing lately and on the dyno Suzuki generally outperform Yamaha for stock power and also what they can safely get them up to. I think it comes more down to design and differences between brands than it does between newer EFI motors of the same manufacturer. Just my thinking..

P.S. surely prop slip will be the biggest factor in economy/efficiency? Real gains to be had reducing this and getting the right prop. Props have power curves like the engines that drive them.

Thanks for this. What is the best method for checking prop slip in a new build. Do I check the maximum rpm wide open and see if it matches the suggested engine specs

[Alex88]

Originally Posted by Ferryman

It should be a bit quieter and a bit more economical. Strictly IMO, they are a bit better but there’s not that much difference.
I would definitely vote for coppercoat, my boat is in the water all year and just needs a lift out in the spring for a power wash - mainly a thin layer of slime.

Thanks. How do you stop growth on the tubes over such a long period of time?. I am happy the CC will sort the hull but the back of the tubes will have long growth in no time.

[Limecc]

Originally Posted by Alex88

Thanks for this. What is the best method for checking prop slip in a new build. Do I check the maximum rpm wide open and see if it matches the suggested engine specs

The faster you go the more the water behaves as a solid and prop slip is naturally reduced so slip at WOT is less important than getting it reduced in the mid-range.

In general terms a larger blade area reduces slip and this achieved with a bigger prop diameter, an extra blade or different blade design. When the blade area is increased then additional power is needed which is compensated by reducing the pitch which will then affect the top speed.
Imho having extra mid-range grip is more important than top speed because the engine will spend more time at those revs than flat out in perfect conditions.

To find out your prop slip you record your speed at 500rpm increments and use an online prop slip calculator to create a chart of your prop slip all the way to WOT. 5% slip is low, 25% slip is poor.

[Ferryman]

Originally Posted by Alex88

Thanks. How do you stop growth on the tubes over such a long period of time?. I am happy the CC will sort the hull but the back of the tubes will have long growth in no time.

Totally unhelpful on RIBnet - I changed to a hard boat. 🤫[emoji16]
There are products available for rib tubes, there’s a recent thread on here?!

[Alex88]

Originally Posted by Limecc

The faster you go the more the water behaves as a solid and prop slip is naturally reduced so slip at WOT is less important than getting it reduced in the mid-range.

In general terms a larger blade area reduces slip and this achieved with a bigger prop diameter, an extra blade or different blade design. When the blade area is increased then additional power is needed which is compensated by reducing the pitch which will then affect the top speed.
Imho having extra mid-range grip is more important than top speed because the engine will spend more time at those revs than flat out in perfect conditions.

To find out your prop slip you record your speed at 500rpm increments and use an online prop slip calculator to create a chart of your prop slip all the way to WOT. 5% slip is low, 25% slip is poor.

Thanks. I will try find the gear ratio and go from there.