SR5.4 with Yamaha F70 4 stroke ??

Bushrider · 22 March 2013, 08:05

What is your opinion about putting a F70 on the transom of an SR5.4 instead of a Yamaha 90hp 2stroke ?

Weight remains the same - while the power drops by 20hp .. fuel consumption significantly lower + range will significantly increase .
Both would be good arguments for the Round Ireland .
Only on fuel the F70 would save me around 1000,-EURO !
Has somebodyy this comnination ?
Cheers

spartacus · 22 March 2013, 08:39

Can't help but think you're going to miss that extra 20hp, plus the Yamaha 90hp is bomb proof if well looked after. The F70 will be fine until you're loaded up...depends how many people you go out with, etc. Having said that the new F70 is ultra quiet, smooth, etc. Coachrib who's a member on here has an XS545 rib with the F70. You could ask him for feedback. Link here for pictures: http://www.rib.net/forum/f37/boat-li...s-45076-3.html

Pikey Dave · 22 March 2013, 08:45

You'll miss the poke of the 2 stroke

Bushrider · 22 March 2013, 09:53

Guys , thanks for feedback !
I am sure the F70 is a cracking motor but I never came accross with one on a similar boat like my SR5.4 .
Last year there was a test of the F70 + a ZAR 4.7 on a German magazine where the Yamaha achieved good results . The ZAR is quite heavy that is why I thought this test could be useful to guess how the F70 would perform on the 5.4 .
I do not intend to participate every year an event like the RI and therefore the savings of fuel during normal annual use would not be that high to justify the purrchase of a new F70 .
I am actually very happy with the 90hp 2 stroke and besides that the motor works well I still have a complete OH kit on the shelve and also a tuning kit which consist of a head with higher compresion , bigger main jets + exhaust manifold . Still hesitate to install these parts cause I consider for the RI the 90hp are more than sufficient on the SR .
Also with all tanks on board the SR will look during the RI more than a supertanker and any additional increase of fuel consumption would be contra productive ..

Rogue Wave · 22 March 2013, 23:17

the f70 has a lot of bang and I'm rather impressed by it. We already have one and I am buying another one for my 4.7 before April 5. Strangely enough I have a 5.4 hull with a 90 2 stroke on it. I'm happy to throw the motor on both boats and if it's feasible as a power plant I'd happily lend it to you/us for the challenge.

I think the 902 stroke is the bestest engine for the 5.4 but I think the F70 will be cheaper to run and thats important!

spartacus · 23 March 2013, 11:08

If you're still looking for an F70... this will be a big saving over new, plus has Yammie warranty, etc. Might be a member in Fife that can check it out, etc?

YAMAHA 70HP 4 STROKE 2010 - FAFB

Bushrider · 23 March 2013, 11:43

Quote:

Originally Posted by spartacus

If you're still looking for an F70...

YAMAHA 70HP 4 STROKE 2010 - FAFB

Thanks for the link ! If this would be just around the corner I would be very tempted

But I am in Ukraine , the boat is in France and the motor in Scotland

I got last year a very reasonable offer from a German Yamaha dealer who offered me the F70 for 7.300,-EURO for a new motor . Need to check whether he would still stick to this price !

Quote:

Originally Posted by Rogue Wave

the f70 has a lot of bang and I'm rather impressed by it. We already have one and I am buying another one for my 4.7 before April 5. Strangely enough I have a 5.4 hull with a 90 2 stroke on it. I'm happy to throw the motor on both boats and if it's feasible as a power plant I'd happily lend it to you/us for the challenge.

I think the 902 stroke is the bestest engine for the 5.4 but I think the F70 will be cheaper to run and thats important!

Stu , I know that for you there`s only one motor for the SR5.4 = the Yam 90hp and I fully agree with you that the power / weight ration is unbeatable - moreover it is extrem fun to run this engine on the SR .
Having spend many hours at sea now with the SR5.4 +90hp I also have to say that I only ONCE I was able to test the top speed which was 70km/h .
In ALL OTHER cases I was never able to use the full power of the engine - except for quick accelerations . My speed is mostly between 30 - 50km/h .
Saying that - I assume that for most cases the 70hp should be enough !
Moreover I compare this with my F100A on my Buster XL . The engine did the job not bad , was economical and quite . I tried OVER YEARS several propeller but nothing really impressed me UNTIL I put a 17" Ballistic on the motor !
Alone in the boat the motor reaches at WOT 6000rpm - it JUMPS out of the water and I can pull easily a tube with still having 5 people on board !
Nothing at all about a slow / sluggish 4 stroke motor anymore !
Coming back to the ZAR 4.7 test with the F70 .
The F70 pushed the boat up to 65km/h with full tank & crew . The total weight of the boat they wrote was 800kg .
My Searider in the current configuration has 800kg WITH trailer !
So between the ZAR & the SR is a significant difference in weight which let me think that the SR performs similar with a F70 !
So on the RI I could skip with my 90l inbuild tank each 2. gas station

taking into consideration a consumption of 0.3l/km and a range of 300km

Oh god - do not let me do something stupid and keep me away from F70 selling people !!!

Mextli · 23 March 2013, 12:28

Keep the 90 Yam - You know how the Boat works with it, you know how it feels. With the F70 (which is by no means a bad motor) the boat will feel different, and you'd need time to get used to it...
Plus, if anything went bang the 90 should be easier to repair than the F70, and sometimes something goes Bang even on new motors.

When does the RI start?

Bushrider · 23 March 2013, 12:42

Quote:

Originally Posted by Mextli

Keep the 90 Yam - You know how the Boat works with it,
Plus, if anything went bang the 90 should be easier to repair than the F70, and sometimes something goes Bang even on new motors.

When does the RI start?

Agree with you - but anyway would be interesting or even worth to give it a try !
RI starts end of July .

C-NUMB · 23 March 2013, 13:03

I have no experience of the the F70. But considering a route/voyage like RI i assume the boat will be heavy loaded with fuel and encounter rough seas(maybe very rough,,,).

Even if the he full power of the 90 Yam is not needed all the time, I would not have anything less than the acceleration and power like the yam 90 in demanding conditions.

Maybe I do I wrong but in some(rough) conditions I use the throttle very actively to maintain
a steady speed(not dropping out of plane), at those situations I doubt a 70 would be enough on a SR 5.4?

Anyone needing a navigator for RI?

Mextli · 23 March 2013, 16:44

Quote:

Originally Posted by Bushrider

Agree with you - but anyway would be interesting or even worth to give it a try !
RI starts end of July .

Interesting it would be
7.800 quid was the deal from your yam dealer? For trying I'd rather buy a Diesel and fit it to the SR for that money. Propably cheaper and more economical.

Bushrider · 23 March 2013, 17:00

Quote:

Originally Posted by Mextli

7.800 quid was the deal from your yam dealer? For trying I'd rather buy a Diesel and fit it to the SR for that money. Propably cheaper and more economical.

7300,-€ , not GBP , not Rubels = EURO and not 7800 but 7300 .
If you find a new motor cheaper let me know .
If you want to test a diesel on your SR go ahead but in another thread please .

Rogue Wave · 23 March 2013, 17:19

At todays exchange rate that works out to about 6400 quid which is a very good price. the box shifters are looking for 6900 over here. i would n't want to loose 3 of the 5 years warranty buying that secondhand engine.

If I am correct the Yammie warranty is worlwide? Does your deal include the controls, props and gauges.

Mextli · 23 March 2013, 17:24

Quote:

Originally Posted by Bushrider

7300,-€ , not GBP , not Rubels = EURO and not 7800 but 7300 .
If you find a new motor cheaper let me know .
If you want to test a diesel on your SR go ahead but in another thread please .

Don't feel offended

I was just sayin' that upgrading the Engine on an already well-engined SR5.4 is more expensive than I'd consider paying for the slight loss on performance.

Bushrider · 23 March 2013, 17:27

Quote:

Originally Posted by Rogue Wave

At todays exchange rate that works out to about 6400 quid which is a very good price. the box shifters are looking for 6900 over here. i would n't want to loose 3 of the 5 years warranty buying that secondhand engine.

If I am correct the Yammie warranty is worlwide? does you deal include the controls props and gauges

Just checked - currently the dealer offers a new engine from 2012 for 7.479,-€ , including control box , prop , 25l tank & digital gauge .
I do not need any propeller nor the tank or the gauge - all is available and installed .
May be there´s still room for negotiations .
Warranty would not be an issue bying being a German and bying from a German dealer .

Rogue Wave · 23 March 2013, 17:29

I was thinking of a Welsh person buying from a German dealer?

Bushrider · 23 March 2013, 17:38

Quote:

Originally Posted by Mextli

the boat will feel different, and you'd need time to get used to it...

was thinking about that too . but the boat feels already very different during all test runs at sea with 180l fuel on board + gear . This is not the stuff I have every day in the boat .
A new motor would require of course new tests but here I could leave the 3 flexible tanks with 80l total capacity at home cause the 90l inbuild tank would be more than enough for any occasion .

Quote:

Originally Posted by Mextli

Don't feel offended

I was just sayin' that upgrading the Engine on an already well-engined SR5.4 is more expensive than I'd consider paying for the slight loss on performance.

right - that is why I decided for the 90hp 2 stroke taking into consideration to use the boat just occasionally .
Now since I registered for the RI the savings on fuel would be around 1.000,-€ which would drop the investment for the new motor significantly

If the F70 would do the job I still additionally have good value in the 90hp Yammi selling it .
To summarize - the F70 would cost me around 3000,-€ under the bottom line .

Even if I do not like the performance - I could sell the motor after the RI and would still achieve a very good price + saved during RI 50% of fuel .
Also an interesting thought ..

Bushrider · 23 March 2013, 17:43

Quote:

Originally Posted by Rogue Wave

I was thinking of a Welsh person buying from a German dealer?

Stu - I can ask the guys next week as for final price and warranty !
Keep you informed !

Bushrider · 25 March 2013, 17:52

made some math with the F70 .
WOT = 5300 - 6300rpm / I would try to reach the upper end of 6300rpm
Gear ratio : 2.33
Looking at propellers with 14 or 15 pitch , 10% slip I would expect the SR to go with 27 - 30kn max speed - see attachment .
With the 90 max speed is 38kn .
To get the boat faster on plane would be an option to block off the flooding hull .
What is your opinion ?

C-NUMB · 25 March 2013, 18:22

Quote:

Originally Posted by Bushrider

made some math with the F70 .
WOT = 5300 - 6300rpm / I would try to reach the upper end of 6300rpm
Gear ratio : 2.33
Looking at propellers with 14 or 15 pitch , 10% slip I would expect the SR to go with 27 - 30kn max speed - see attachment .
With the 90 max speed is 38kn .
To get the boat faster on plane would be an option to block off the flooding hull .
What is your opinion ?

I would block it, it is still very stable, and transom is still rather low.....I blocked it 2011, last summer there was not even condensation moister inside when checking, totally dry.

What consumption You expect with the F70 when doing 28-29 knots?