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I am new to Whaler Central and am in the process of a Nauset 16 restoration. I have my eye on the Yamaha F70 for many reasons including it being light / quiet / efficient / new technology, etc. I know the prop makes a difference -but if it is set up right. What kind of speed & performance are folks getting with the pre-smirk 16/17 hulls? Mine would have a center console and would not have tons of gear or fuel or people or water skiing, etc. I believe I have seen folks are getting around 37/38mph? Any help or suggestions are greatly appreciated.
Thanks,
Scott

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If mounted correctly, 2 holes up, with the appropriate prop, 36-38 mph at WOT should be attained.

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Mount the motor Three Holes Up if using a Stiletto, Turbo or Yamaha Performance Series 3-Blade propeller. The ideal size 13-1/4" x 14" and you should see a top speed of 38 MPH.

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Thanks I really appreciate the info. 37-38mph top speed is was what I have read for the yamaha F70 so good to hear you guys have the same info. The other option is a 90 etec but that is about 65lbs heavier and again I would really like a 4 stroke for it being quiet and not to have to burn oil, etc. Sounds like this hull will get to the 42-44mph range with a 90 etec. So is it true with the 16ft hull going from a F70 to a 90etec (increase by 20hp and 65lbs of weight) you pick up about 5-6MPH in top end speed?

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You are thinking about old 2 stroke technology.
The new 2 strokes are just as quiet, fuel efficient as a 4 stroke and generally weigh less.

The Yamaha 70hp is hard to beat for the weight of 257 pounds.
If you want to go with a 90hp, here are your other current choices with the weights listed.
http://www.whalercentral.com/articles...ticle_id=5

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Is there anyone else out there with an F70 that can share their experience? Maybe I'm wrong but I imagine the F70 is indeed quieter than the equivalent fuel injected 2 stroke. I know 4 stroke Yamahas very well and have been on plenty of boats with fuel injected 2 strokes and don't get me wrong I like them both, I am just not familiar with the F70 on this hull. I was thinking of running with only two 6 gallon tanks. They are more portable and everyone I have spoken with says the engine sips fuel, which is nice.

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I have 2 of the 16 foot with same hull as the Nauset. One has a 2-stroke 90 hp Yamaha, the other a 70 hp two-stroke yamaha. The 70 is almost new as it was a leftover and I bought two years ago "new". It is very quiet and pushes the boat at good speed with 18 gallons of fuel and four people. It does use more fuel than a four stroke. The boat with the 90 hp is very fast. I have only run it by myself, so I cannot give feedback about the performance with a load, but it almost seems like more than you need unless you are really into speed. I allow my kids to take friends out on the one with the 70 hp but I would be nervous letting them on the 90 hp.
Even though I am not in the market to re-power either boat, the F70 sure seems like a great fit { the 4-strokes were a little heavy for my liking when I pulled the trigger} Having read about the E-techs, I would think the 90 hp would be way more than needed.

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Hi Scott,
I have a Yamaha F70 mounted on my 1988 Montauk 17, and am quite happy with it. The motor is mounted 3 holes up, and I am running a Stiletto 13.25" x 13" prop. It seems to be a bit under-propped, as I can pretty easily get the motor to rev-limit. The boat can reach 36MPH with me (220#, but I'm working on it) and 23gal of fuel. Best planing milage is 7.5-8 MPG cruising at 21MPH, around 4000RPM. Between the lightness of the Yamaha and moving the battery to the console, the boat now rides 2-3" higher in the stern that it did previously.

Hope this helps.

Dennis

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The ideal prop would probably be the 13-1/4" x 14" Yamaha Performance Series 3-Blade. I've been trying to find one for Dennis to test.

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I have an F70 on my 15, and I get 9 - 10 mpg at cruise of around 4000 RPM. I'd imagine you'd get a bit less, but not much less.

I don't have an eTec, but having heard them on other boats I don't think they're a lot noisier than a 4-stroke, if at all. Don't confuse eTecs with transitional technology FI 2-strokes such as the Optimax or Yamaha HPDI - they're different, and much noisier, beasts. It there was an eTec 70 I probably would have bought it, although I do like my F70.

Most people ask: 2-stroke or 4-stroke?
They should ask: Today's technology, or noisy, smelly yesterday's?

Tim

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Hey y'all, I installed a Yamaha F-70 on my 1970 Nauset this past fall. I couldn't be happier. I mounted it 2 holes up on the transom. My top speed is 38 mpg with a stock Yamaha stainless steel 17" pitch prop that will turn the engine 6000 rpm trimmed up. Most of my running is in the 4000 rpm range that gives me a mid 20's cruise. The weight is correct for the older hulls. No smoke, it's quiet and has plenty of power. I haven't water skied yet with it, that will come when the water warms up.

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There is no such thing as a "stock Yamaha stainless steel 17 pitch prop". The F70 comes out of the crate without a propeller and one must be selected for it by the dealer or owner.

Yamaha makes several different models of stainless steel propeller to fit the F70. Which one do you have?

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I have the painted stainless steel propeller part number 688-45930-02-98. The reason I called it "stock" was that it's not the 4 bladed, polished etc...

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Whether it is painted, or has four blades, has nothing to do with being "stock".

The Painted Stainless Steel model form Yamaha is a good propeller model. It is the ONLY model of stainless steel propeller Yamaha offers that is not made in the USA by the PPI Inc. division of Yamaha.

The Painted Stainless Steel model also has a unique semi-cleaver blade design with modest rake. It is good for stern lift and faster than most people think.

For the F70 and all the other intermediate size gearcase motors, there are five different models of propellers to choose from branded as Yamaha.

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I ended up picking up a used yamaha F70 with 134hrs that was very well cared for by someone I know well (who is also a yamaha master mechanic). I really feel lucky to have found it. The F70 is now going on the 1989 montauk...so my plan changled slightly. The motor didnt come with controls or a prop, so I have to order everything and rig it all up. I will also be moving the batt to the console all at the same time. All that said, I have a bunch of questions and would really appreciate your thoughts/suggestions/insights. All the help you have given me thus far has been great - so Thank you.

- how long should the control cables be? I would like them to be the right length w/o extra. from the research I have done, I am reading 15 or 16' feet. do yamaha cables only come in 5' lengths? if so is 15' enough? there was a thread here (that I can't find) that showed pics of Toby Port's (fellow whaler central member) montauk with and F70 and the rigging looked super clean with the right length of control cables. I would like mine to look similar.

- prop it seems like the size is 13 1/4 X 13. I would like a aluminum prop vs. stainless (personal choice for a few reasons) any recommendations? for some reason I can find stain less props but having trouble finding an aluminum 3 blade prop that size. Is anyone familiar with the Solas Amita 4, 4-Blade Aluminum Prop, Fits Yamaha/Tohatsu/Nissan 60-140 HP, 13.25 x 13-P RH #3413-133-13? Any advantages / disadvantages to a 4 blade?

Here is the other rigging im picking up (hopefully I am not missing anything)

6YR-W0035-E3-00 TACHOMETER RIG KIT 2

Yamaha Optional Primary Engine Harness 10-Pin 5m (16 ft.)

704-48205-P1-00 CONTROL, BIN PRM SGL

Yamaha Single Main Switch & Stop Switch on Panel (Horn)

MAR-Cable-Sc control cable (size ?)

alumn prop 13 1/4 X 13 (kind ?)

Again I really appreciate your thoughts/suggestions/insights.

best
Rufus

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Hi Rufus,
I have this same motor on my 1988 Montauk. I installed the Teleflex extreme CCX63320 cables. These are 20' long. I added the loop as they exit the motor (per the rigging length information on this site) to minimize friction and wear. I think it looks pretty clean. The loops stay above the splashwell.

I have a Stiletto 13.25 X 13" SS prop, and the motor is mounted as high as it can be (3 holes up). It may be a bit under propped, but the 15" was too long.

I have moved the battery into console as well. It is connected directly to the starter with around 17' of 6ga cable, a single piece. It works very well, starting the motor with no hesitation.

I'll take some photos Saturday, and maybe even try to put up a personal page.

Dennis

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The 13-1/4" x 14" Yamaha Performance Series 3-Blade is probably the best choice of the Yamaha propeller options. Unfortunately, the 14" pitch is not offered in the Stiletto (Advantage) or Turbo (Turbo 1) versions.

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Thanks, that is helpful
sry that was a type-o on my part I meant to say 13-1/4" x 14" prop.. for some reason I am having trouble finding this size in an alumn prop?

it seems like I am hearing everything from 15' - 20' for the cables? I would like the not have extra, but have it set up correctly

should it be mounted 2 or 3 holes up? in my searches I have found people mounting an F70 both ways on a Montauk

thanks again

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Propellers are not generic pieces of hardware simply described by diameter and pitch. Size recommendations are specific to the model of propeller being discussed.

If you use an aluminum prop you'll probably want a 15" pitch.

If you use an aluminum propeller, you will not be able to mount the motor as high.

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These are all the Yamaha branded propeller options for the F70:

http://www.yamaha-motor.com/outboard/...0~F115.pdf

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Thank you very helpful. so if i were to pick an aluminum prop you suggest a 15 pitch so this would be the only choice. Is this what you would suggest? do you think I would still able to get 37/38mph on a 1989 montauk?

- 13 1/2" 15(pitch) 3 (blade) Aluminum pressed in 6E5-45947-00-00

- would you go 2 or 3 holes up?

- any other suggestion for control cable lengths?

I am really have to move forward with mounting the F70 and rigging it up.

Thanks again for all your help and suggestions - Whaler Central is tremendous.

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May I ask why you are set on an aluminum prop? Seems a shame to saddle that nice new motor with yesterday's technology.

Tim

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The Teleflex Extreme cables I have are universal, not Yamaha specific. On the Black Bear Sporting Goods site I see 16', 18', 19', & 20'. There are likely other sizes too. You just need to dig a bit.

Dennis

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so if I were to go with an aluminum prop would this be the prop (below)? Tom this is the only choice for a 15" pitch. does anyone have experience?

13 1/2" 15(pitch) 3 (blade) Aluminum pressed in 6E5-45947-00-00

looks like I could also potentiall use these (see below).

13 5/8 14 (pitch) 3 (blade) Aluminum pressed in 6E5-45958-00-00

13 5/8 13 (pitch) 3 (blade) Aluminum pressed in 6E5-45949-00-00

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As a point of reference, you can get a new Stiletto Advantage 1, with the required DE-500 hubkit, shipped to your door for $261.95. A 13.25 x 13 would be perfect for your application, and will perform much better and last much longer than any aluminum prop. You may be able to find a used one cheaper - I sold one last year to a guy who's using it on a Montauk.

It looks like the Yamaha aluminum props can be had online for about $150, which is indeed cheaper. I'm still not understanding why after spending many thousands on a new motor and rigging, someone wouldn't spend just a little more to get it to perform optimally. But of course it is your choice.

Tim

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Those are the only choices form Yamaha but all other manufacturers make aluminum props too that would fit your F70.

Propeller manufacturers generally only make one model of aluminum propeller in a class simply because there are still those who want to use an aluminum prop for whatever reason. They also make good emergency spares.

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Tom/Tim, Thanks for all your input. I do have to decide the prop and from what you guys are saying (and my research) it seems the best prop choices are the following. Now i have to figure out how to pick one.

Yamaha 13.25 X 14 P (stainless)

13.25 x 15" Stiletto Advantage (stainless)

13.25 x 13" Stiletto Advantage I (stainless)

Yamaha 13.5 X 15" aluminum prop?

I was just thinking aluminum because there is a lot of shallow areas in my local waters and I was told in the event you ground or impact floating debris an aluminum prop would cause less damage to the motor itself because aluminum is a softer metal. Anyways, im sure there are a lot of opinions out there on this subject.

and it seems 18' control cables?

Thanks again everyone for all your help and suggestions. it is all very appreciated.

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Yes, that is a common myth. Might have had some relevance thirty years ago, but not today.

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Scott,
I do not think you'd be too happy with the Stiletto 13.25" x 15". I tried that first (carry-over from when the motor was mounted on my 15' Sport CC), and it was very sluggish, even with just me. I was not able to get to WOT, only about 5400RPM.

The Stiletto 13.25" x 13" is much more responsive, and gets on plane with 4 & 23gals of gas. I haven't had the opportunity to load it more heavily. However, with just 1 or 2 people, it will rev-limit the motor. I can still get to about 36mph.

The Yamaha 14" pitch propeller you referenced might be ideal for the lightly loaded boat, if that's what you'd like to optimize for.

Dennis

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I just put an F70 on my 1963 custom (originally a Currituck).
I have a center console, leaning post, batteries (2) in the console, and a 22 gallon gas tank under the leaning post.
Just like you, I went with an aluminum prop. I used a 13 1/2 x 15 Yamaha #6E5-45947-00-00.
The dealer set everything up and I could not be happier.
I can not answer top speed for you, I am not out of the break-in period (10 hours) so I haven't been at WOT.
I can tell you that with three adults and the dog on board, there is power to spare. The boat floats on its lines and looks like a Whaler should.
You will love your F70.

Best of luck,
Gary

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http://www.arimaowners.com/index.php?topic=778.0

here is an interesting link i found with F70 prop data for a 16' boat. Its not whaler data, but interesting nonetheless.
looks like they tested the Solas 4 blade prop which is one I was looking at.
Solas Amita 4, 4-Blade Aluminum Prop, Fits Yamaha/Tohatsu/Nissan 60-140 HP, 13.25 x 13-P RH

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Also check Yamaha under 'Performance Bulletins' for F70.
Use skiff for 'Boat Type', it lists a 17' Key West. Very similar in style and weight to our boats.
It will give you a great deal of info including a top speed of 36.6 mpg @ 6300 RPM.
Anyway, check it out.

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Old thread - but I wanted to circle back regarding the prop conversation to learn more about Pitch & Size and Aluminum vs Stainless, to help me better understand the pros and cons.

Here are props I have my eyes on (all 3 blade):

- Stainless Yamaha Performance Series 13-1/4" x 14"

- Stainless Stiletto Advantage 13.25 x 15"

- Stainless Stiletto Advantage 13.25" x 13"

- Currently, running Yamaha 3 blade aluminum 13 5/8 x 14"

I am overall happy with my current aluminum prop I am running. A bigger prop than the SS examples above and at WOT I can achieve the 6300 rev limit.

I'm curious what perf and speed advantages I may have with a stainless prop and if it is worth it.

The F70 is on a 1989 Montauk. 22 Gallon tank that is usually half filled. Batt in the console. No water skiing, towing, etc. Light load most of the time. 1 or 2 people with minimal gear, mostly a couple of fly rods.

As a side note, I still have the 16 Nauset (hence the thread titile), but it is still a project... and needless to say the F70 never made it on that hull and ended up on the Montauk.

I would appreciate your thoughts

Tom/Tim/Gary - thank you and others for all the prop advice through the years in this thread and other threads.

Thinking on boating in January

All the Best,
Rufus

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Both Tom and Tim have more prop expertise by far than I do. I will say this though. There is no reason at all to use an aluminum propeller.
In the good old days Yamaha sold all the motors above 30hp with stainless props. When I replaced my 1985 70hp 2-stroke with the same motor in 2007 it came with aluminum. I took the 22 year old stainless off the old motor which I sold. I gave the buyer the new aluminum.

By the way I run in shallow water constantly and run in sand or mud almost every trip at some point.

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With respect to aluminum vs. stainless steel and the idea that the former will protect you from impacts, it is indeed an old wives tale. It was effectively, and to my mind finally, debunked a few years ago on this very forum, where a member reported two separate boats hitting a submerged post in his harbor. One had a stainless prop, and the other aluminum, and both boats destroyed their lower units - the aluminum provided no protection.

So aluminum won't save your motor, but it will cost you some fuel economy and performance - fairly subtle, but real. And aluminum will take damage from floating debris or shell flats, while stainless will shrug it off with a few scratches.

Regarding the prop choices you list, my choice, based on my experience with the F70 on my 15, is "none of the above." My short list for an F70 on a Montauk would instead be the Yamaha Painted Stainless (YPS) mentioned by Aquanutt on the first page of this thread, the copy made by Power Tech which is the SCD3 model, or possibly the Turbo Quest.

I used a Stiletto Advantage for several years, but was never really satisfied with acceleration and top end. After thinking about it for quite a while, I theorized that with the F70's power curve, I wanted a prop with less blade area to let it spin up easily through the middle RPMs to get to where it makes its power at the upper part of the RPM range. I contacted Power Tech and after some discussion, they recommended the SCD3. Subsequent research brought me to look at the Turbo Quest, which has the same characteristics as the SCD3 and YPS - smaller blade area, low rake. The Quest is specifically advertised by the manufacturer as being a good choice for the F70, so that made me think I was on the right track. The Quest is, however, more expensive than the others. I went with the SCD3 as it was a little cheaper and they let you trade in if the pitch isn't right. I am very happy with that choice.

Don't get me wrong - the Stiletto and other large blade area props are great, just not right for the F70, based on my experience. The difference when I switched to the SCD3 was like night and day, and it made the boat much more fun. Acceleration is instantaneous, and top speed improved as well. Most impressively, I can get very close to top speed without trimming out at all - something I need fairly frequently in the areas that I boat in.

Regarding pitch in the SCD3 or YPS, I would characterize Aquanutt's 17-pitch as just a bit too high, and I run a 16-pitch which is a whisker low for my 15 but might prove optimal for your Montauk.

Tim

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I have a 1999 Alert 17 with a Yamaha F70LA on it with a Yamaha Performance Series Stainless Steel 13.25 x 14 prop mounted all the way up. From my experience what Tom Clark says is spot on.The boat handles great and with me alone,flat lake,trimmed up with about 12 gallons of gas I can get very close to 38 mph and with a slight chop 36.7 mph all day . Thanks again to Tom for helping me to set this motor up,my dealer said I would be back to have my motor lowered and was suprised when I told him it performed perfect.

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Alan, to add to the data, what RPM are you turning at those speeds?

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. According to my Yamaha digital tach 6300 rpm.

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I have the Stiletto 13.25" x 15 on my Montauk and with my average load I'm only getting 4600 rpm on my Yamaha 90hp 2 stroke. I'm mounted 2 holes up and moving to 3 but I need more pitch.

That said, if anyone with a lower pitch prop that wants to try a trade let me know and we can work something out.

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Thank you all for the helpful advice & feedback. I must say a lot of info to digest.

Since the F70 is a higher RPM motor, smaller diameter prop? To maximize speed, higher pitch?

Again Currently, running Yamaha 3 blade aluminum 13 5/8 x 14"

Sounds like I have potential to really increase my performance & speed vs. what I am currently running. That said, I want to do my homework to get this right.

I'm still not sure what stainless size & pitch to aim for, for my hull & outboard, and for my applications (from my previous posts).

Here is everything I have heard:

Brands:
Yamaha Performance Series
Yamaha Painted Stainless (YPS)
Power Tech SCD3
Turbo Quest
Stiletto Advantage

Diameter & Pitch:
- 13-1/4" x 14"

- 13.25 x 15"

- 13.25" x 13"

- 13.5" x 16"

- 13" X 17"

By the way
Interesting article re: prop pitch
http://www.boatingmag.com/how-to/understanding-propeller-pitch

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I am running my 1967 Nauset with a 90-hp Yamaha 2-stroke. Currently, it is set up so the motor is 2 holes up. I am using a Yamaha Stainless Performance 3 Blade Propeller 13 1/4 x 16 MAR-GYT3B-V4-16 (310429904135) FedEx Ground or FedEx Home Delivery $450.14 on eBay. This prop works very well. However, you ought to know that with the 2-holes up configuration, I need to power tilt the motor to a rather high tilt so that there is not much spray coming from the cavitation plate. Otherwise, there is quite a bit of spray flying side-wise off of the cavitation plate.

With the motor tilted this far out, I am getting close to, but have not yet reached, the point at which water will no longer be fully available to the cooling system. With one person and a single gas tank, the boat is running at about 42 m.p.h. top speed into the wind. I've noticed that with this motor, adding some extra weight to the stern raises the bow to allow a faster speed. This is accomplished my moving fuel tanks to the rear. Eventually, I might move the console and driver seat back 4 inches or so to improve the ride. If you could get one, I think the older tower of power 100 - 125 hp Mercs would be a better choice for top speed since they are heavier.