Yamaha 25 hp high thrust mystery

[kolyo]

I'm unable to find anywhere in Europe the new Yamaha T25 high thrust model, weighing only 70 kg. (in the 25" shaft version) with a gear ratio of 2.08:1
Yamaha Outboards

Widely available is the FT25 model one but it is much heavier (nearly 100 kg) and has a gear ratio of 2.42:1
Yamaha FT25FETL 25HP High Thrust Long Shaft Outboard

Which of the two is the "true" high thrust model?

I'd prefer the lighter one but with it's 2.08:1 gear ratio, usually found in the F models, it doesn't seem right.

Can someone shed light on this mystery.

 

[Boathook]

Just following your link that, as you say a brand new model as it is fuel injection rather than carburetor. That is the USA site so possibly to follow here, so I suspect that they will be trying to shift the old model first. The picture of it shows a dual thrust prop so I assume high thrust.
The EU/UK site doesn't mention this fuel injection version at present, only the old carb one.
Yamaha T 25hp - Features and Technical Specifications
I will have to start looking again at this model when available in the UK to see what else has changed apart from the weight.

 

[kolyo]

So, the lighter weight EFI T25 is not available in Europe for the time being, huh?!? A bit pricey to order it from the US, Australia or Canada

 

[ontheplane]

You might be able to order it from a Yamaha dealer, they may just not have it as a stock item till Yamaha sell out the old one.

 

[kolyo]

You might be able to order it from a Yamaha dealer, they may just not have it as a stock item till Yamaha sell out the old one.

None of the Yamaha European dealers that I've contacted would accept an order for the new lighter weight fuel injected T25. Even at the main EU supplier hub stationed in The Netherlands???

Still a dream for Europe: https://yamahamarinemedia.com/wp-content/uploads/2019/01/YAMAHA-T25-Hot-Sheet-Final-1.pdf

 

[lenten]

i thought hi thrust was defined by gear ratio ---2 1/2 to 1 as opposed to 2 to 1 which is standard

 

[kolyo]

i thought hi thrust was defined by gear ratio ---2 1/2 to 1 as opposed to 2 to 1 which is standard

So did I. The legendary FT9.9 is nearly 3:1, which ratio Yamaha retained in its successor, the T9.9. Sadly the T25 doesn't have the 2.42:1 of its predecessor FT25. I wonder if it's just the larger, lower pitch prop that gives them the right to call it a "high thrust".

 

[C08]

I find it hard to beleive the weight is really 70kg for the high thrust engine. The Yamaha spec sheet for the T25 then gives the weight as 92kg but then refers to it as FT25 when listing the weight. As far as I know the 2.42 gear ratio is within a heavier built gearbox (certainly looks bulkier) which explains the higher weight than the 2.08 gear ratio and lighter weight of the stanadard 25HP.
Edit: the weight really is 70kg on checking-I have an interest as bought a FT25 last year!

 

[C08]

I have just loooked at the spec sheet for the new T25-lots of new features there for this new engine over the FT25. Yes 70kg inc PTT, only 432cc rather than 498cc but this parallels cars which now have punchy engines of 1000cc in average size saloon cars, the good thing is they do a 25" Xlong shaft which is not available in the FT25, higher power alternator and variable trolling speed. I am not sure whether EFI in the contecxt of a boat is progress of not but should enable better fuel economy. They are coy about the prop size though and only give the pitch as 6.75 for the X long shaft but not the diameter of the prop?
The Hot Data Sheet is dated Dec 10 2018 so really not very new?

 

[kolyo]

The all important (to me at least) question is "Are Yamaha misleading potential buyers that the new 30% lighter, fuel injected model with the extra long shaft option has the same high thrust capabilities of the much heavier carbureted version. perhaps someone more knowledgeable would care to comment this video

 

[ontheplane]

The High Thrust moniker applies to BOTH the prop and the ratio - one without the other wouldn't make it proper high thrust. I know you can fit the high thrust prop to the standard motor but to my mind will still be spinning too fast to get the revs up to produce the hp.

 

[BruceK]

The High Thrust moniker applies to BOTH the prop and the ratio - one without the other wouldn't make it proper high thrust. I know you can fit the high thrust prop to the standard motor but to my mind will still be spinning too fast to get the revs up to produce the hp.

Not necessarily. One can achieve torque and lower the rpm's with reed valves and longer cylinder stroke.

 

[kolyo]

Not necessarily. One can achieve torque and lower the rpm's with reed valves and longer cylinder stroke.

Does the lighter 432cc T25 have reed valves and longer cylinder stroke than the 498cc T25?

 

[C08]

On the video is seems to show a 10 5/8" size prop which is the sort of size you may expect with a 25hp with conventional gearing. The prop on the FT25 is 13". Although the new motor has many new features I think it is different to the FT25, in many ways it is better but the very thing which people want in a high thrust engine for a displacement hull is missing. I have the impression that the T25 has manual as well as electric start; I only noticed my FT25 did not have a recoil manual start after a couple of weeks of use!

 

[Boathook]

On the video is seems to show a 10 5/8" size prop which is the sort of size you may expect with a 25hp with conventional gearing. The prop on the FT25 is 13". Although the new motor has many new features I think it is different to the FT25, in many ways it is better but the very thing which people want in a high thrust engine for a displacement hull is missing.

The 10 5/8" by 8 1/4" prop is the one I had machined to fit my Honda 30 that has a standard gearbox for a speed boat. Does this mean that yamaha are dropping the ft25 for the lighter model. That new engine won't have the same power for pushing displacement boats as the old one in my view.

 

[kolyo]

...That new engine won't have the same power for pushing displacement boats as the old one in my view.

I agree. The gear box of the new one looks standard to me. The most annoying thing is both models are labeled T25 which can make buyers think the lighter of the two is a true high thrust motor.

 

[C08]

I have been down the road of a slightly bigger prop and finer pitch on my 20 hp Tohatsu and 3 to 4 blade and the differences were small apart from astern which was much better.
i have only used my FT25 in running in mode(only 10 hours) so not able to comment fully but early indications are very positive.

 

[kolyo]

i have only used my FT25 in running in mode(only 10 hours) so not able to comment fully but early indications are very positive.

Even so, please tell us more about your application. What made you go from 20hp Tohatsu to FT25?

 

[C08]

On a 3.5 ton sailing catamaran. The 20hp Tohatsu was ok most of the time but occassionally trying to motor against wind and tide I felt a bigger engine would help as a cat has a lot of windage. So an extra 5hp with a 13" prop compared to 9" and with better gearing seems a good idea and the Yamaha engine looks more substantially built than the Tohatsu.
If you want a FT25 you may have to get on with it as I cannot see Yamaha continue to market 2x high thrust 25hp motors?

 

[kolyo]

If you want a FT25 you may have to get on with it as I cannot see Yamaha continue to market 2x high thrust 25hp motors?

I'm trying to find the most suitable trolling/get home aux motor capable of pushing my 2.8 ton flying bridge planing boat at hull speed in 10-15 knots headwind without compromising too much the ability of 310hp main I/O engine to get on plane. The old FT25, weighing nearly 100 kg. seems too heavy, that's why I'm investigating the new 30 kg less weight T25. Unfortunately the lighter weight comes with a serious reduction of low end thrust which is paramount for my needs. The nearest to the well proven but insufficient for me Yamaha 9.9 high thrust is the extra long shaft Honda BFP15 , weighing 52 kg.