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I just purchased a really clean 2005 Yamaha two stroke 90 to be installed on a 1988 Montauk. I've found some info through searching and realize there is a ton of info that is confusing me.

13" x 17" Yamaha Painted Stainless Steel
13-1/4" x 16" Yamaha Performance Series Three Blade
13-1/4" x 15" Stiletto Advantage 4.25
13-1/4" x 15" Turbo 1 4.25

This is the list that I've found here and on the other site. Tom seems to recommend the stiletto quite a bit, and I'm leaning towards that prop, but my question is, is the hole shot good with this prop? also should I see 40+ mph with this prop? I'm ready to pull the trigger now on buying, I just want to make sure I get it right the first time. I really would like to see 40+ if I can without sacrificing much hole shot. If this is the correct prop for my setup, where is the best place to purchase? Thanks for the advice in advance.-Jack

(changed abbreviated year to full 4 digit year for clarification)

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Hello yet again jaxmyth, What is the intended use of your 17 Montauk? What cargo loads (people, gear, etc.) do you expect to have from time to time.

Obviously there is a noticable difference between your Whaler and mine even thought we have like outboards.
I have run two props on my Dauntless 15 and have noticed differences between them. I typically boat with my family (4 of us plus snorkling gear, and cooler with treats). Our two kids are late teens so adult weights are in play.

My first prop was a Solas 13-1/4" x 17P (Round ear 3 blade) in Strainless Steel. The Round-Ear props are refered to as "Bow-lifting" style. Getting on plane promptly is not this props best trait, once on plane good mid-range to top-end. I try not to push beyond 5200 RPM's if not needed, MPH on GPS around 38 to 40 (with near perfect smooth chop) and with loads mentioned above. This prop gets off plane very quickly if slowing down while negotiating chop and swells!!!

My second prop (purchased used but in excellent condition) is a Power Tech 13" x 17P (Semi/Cleaver 3 blade) in Stainless Steel. This prop is refered to as a "Stern-lifting" style due to the semi-cleaver (shark fin) blades and is very similar to the Yamaha prop you mentioned in Black trim. I get "out of the hole" or on plane in half the time and with less engine effort than I did with the Solas having same loads. Mid-range to top-end pull is consistant, again I try to stay below 5200 RPM's but there's still throttle left for a 5500 push if I needed it. MPH on GPS is between 36 to 38 (with near perfect smooth chop) without pushing the Yamaha 90 hard.

I now keep the Solas as a back-up/spare for a "just-in -case" day. From your posted selections I viewed a few props with 15P, these are suggested?

Hope this helps...
Best,
Angel M.

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Dauntless, thanks again for the reply. I mostly use the boat for fishing with two adults and coolers and fishing gear. but I do use it occasionally for cruising with my wife and two small kids. I don't normally have a heavy load in the boat and mostly cruise in the intracoastal and st johns river. i'd rather be able to hit 40 to outrun some storms in the river and maybe pull a tube with the kids.i won't be pulling any adult skiers out of the water or anything like that.

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Sounds good, then perhaps the props with smaller 15" pitch will give you the low-end punch. I suspect with the size and weight of your Montauk and if looking for a 40 MPH running speed (when needed) you will eventually over-spin the 15" Pitch.

Is there a possibility with a local boat/prop shop you could do a "lend-lease" process to test the diameter versus pitch theory? Down here in Miami, FL we have numerous prop shops that will afford us boat owners this service and in turn they hope to gain a customer which I think is good business.

Do some research on the two types of prop designs Semi-Cleaver versus Round-Ear you may find the topic interesting depending on the weight distribution of your Montauk and if currently stern heavy.

Best,
Angel M.

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I have the 13.25x15 Stiletto Advantage on my 1966 16'7" with a 1989 Yamaha 2-stroke mounted 3 holes up.
It absolutely flies with an excellent hole shot. I now cruise at 2800 RPM and have been at 5100 and 43 MPH.

I have yet to run wide open but expect I would see 45. This prop and motor came on the boat, I did raise the motor. If I were to search for prop advise Tom is where I would turn.

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I have the Stiletto mentioned above on my 1989 with 1998 Yamaha 90 2 stroke (great engine btw). I carry a lot of gear and it's still mounted in the blind holes/all the way down but I'm only getting 4400 RPM and 31kts WOT with my average load.
I plan to re mount the engine but don't think it will make that much of a difference. I rarely need/want/have the opportunity to run faster than that but wonder if there's a governor/throttle adjustment I could make or if I just bought the wrong prop. I only gained a couple kts and rpms from my old aluminum.
Ps: how much did you pay for the engine. If mine dies tomorrow I'd be torn between a used 90 / 2 stroke vs 70 / 4 stroke.

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I'm trying to figure out the right height to mount mine also. I believe your issues will be the height that you have it mounted. I was hoping Tom w Clark would comment. I really hope the stiletto gets me the performance I want. I rarely have a heavy load in the boat. I ended up paying close to 5k for the motor, which is higher than I wanted,but the condition of the motor is impeccable. It was truly a freshwater gem. I would have loved to purchase a new 4 stroke 70 to replace my old 2s 70, but price was a factor.

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I was a bit of a skeptic about the performance gained by raising the motor. It just didn't seem that it could change that much. I do not have apples to apples yet because while I have two identical hulls [1966+1964] the motors are a 90 Yamaha 2-st on the 1966 and the 1964 has a 70 Yamaha 2-st.
The 70 is the one I have been running for many years, and I did a lot of work on it this spring. It is now water ready and has the motor up to the third hole just like the 90.

If the added performance is anything close to the 90 I will be extremely happy. Hole shot is so fast, and I am now cruising at almost 1000 RPM less than I used to, and going faster. I believe the 70 is very adequate power for my boat, but the 90 is probably a better fit for the Montauk.

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Jax,

I am running a 90 E-Tec on my boat so not apples to apples with your situation, however it replaced a 1989 90 HP "Mercaha" that was very similar to the engine you have. The old motor was mounted all the way down on the transom and would turn a 19" Solas aluminum prop to about 5000 RPM (over 3 years ago at this point so my memory is fading on the specifics) and 40-41 GPS if I trimmed it out enough. The 13.25 X 15" Stiletto acts much more like a 17" pitch prop, in fact the other prop that was recommended here when I repowered was the BRP 17" Viper stainless. The Stiletto has relief holes in the hub that help with the hole shot, if you have a healthy engine and not too heavy a load it should be a good match. Mount it at least two holes up, most here will recommend three holes up. It's a great all around prop on a 16 / 17 with a 90 HP engine. I've seen 43 GPS at 5200 RPM light load on mine, I'd be surprised if you didn't see similar numbers with yours. Good luck.

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I could have this wrong but I think I read somewhere that each hole I raise the engine will gain me about 1000 rpm and 1.5 mph top end. I know it needs to be done but just haven't gotten around to it yet.

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WhalerBob -

The general guidance on raising the engine is for each hole the motor is raised, one would gain 250-400 rpm.

I personally saw an increase of 224 rpm for each hole raised (motor was a Yamaha F1150

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Thanks Phil, that's probably why I've been procrastinating this one. Is there another prop or anything else I can do to boost my performance? I gained about 2 kts with the Stiletto but this is pretty much how it's been since new.

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ok, so I've had to mount the engine using the blind holes so I don't have to drill new holes. does that mean the engine is all the way down? if so, instead of the stiletto prop, which prop should I get? I really do not want to have to drill new holes and plug the old ones.

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I guess basically what I'm asking is, instead of drilling new mounting holes, what would be the most appropriate prop to get with the best performance given the current holes that I'm using. "blind holes are being used" and the anti cav/ventilation plate is even with the keel.

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If you read the old thread I re-posted you will see that I was also hesitant to drill the holes and raise the motor. It probably took an hour total time the first time.
On the second boat it was probably 15 minutes. By myself both times, although I did use a Bobcat with a cable to the hoist ring built on the motor the second time. Used a thick epoxy fairing compound for the old holes, but as others have said a dowel soaked with resin would be fine.
I predict when you do it you will be amazed and your only regret will be not doing it sooner.

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Mtown, do you have any pictures of your install? and you're using the third holes down in the top set of holes?
Also, I tried to order the stiletto advantage 1 prop from boatownersworl.com and they don't have it anymore. I called dansprops to see if he had it and was told he would have to check with his distributor and that he'd call me back. but I never received a call. are there any other places to get that prop if I do re drill the holes?

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Hello jaxmyth, there is one option if you really prefer not to re-drill the transom. You could consider a manual "jack-plate" with minimal set-back (4 inches or less if available). If this seems reasonable you would need to research for a model/type which may have your current bolt-hole configuration or re-drill the 2 lower holes into the jack-plate to match your transom.

This was just a thought. It offers ease of height adjustments and without having to fuss and re-seal mounting bolts through the transom if doing further height adjustments. I wish I would have done this when I had my outboard dismounted sometime back. I will definitely consider this method and with hydraulic steering the next time my motor comes off. I've seen some reasonable prices on ebay if this helps.

Happy boating...
Angel M.

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Ok. well it appears as if I need to just plug the holes and redrill. what type of plug should I use to fill the holes with and what epoxy? also, when I redrill, do I put the motor on the transom with the top two bolts in the bottom two holes of the top four in the motor and then drill which hole in the bottom?

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If I understand what you're saying that's how I planto approach it.
1) take motor completely off and I would pack the hole with fiberglass matting soaked in epoxy, gelcoat, and sand smooth.
2) mount the engine on the transom using the top two bolt holes at the desired height and use the mounting holes of the engine as my guide/template for where to drill the bottom holes. (I don't have the diagram in front of me but I think I am going for the green holes so they are as high in the splash well as possible.
3) remove the engine, blob marine silicone in the holes then replace the engine and bolt everything tight.

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Jax
sent a PM . Will send pics but cannot post here. No outside account for that.

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Bob,
Sorry I just saw you are in MD also. Let me know if you want me to come by to help. I am northwest of Balt. but also go to Annapolis/beach on some regularity.
Scot

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Mtown, that's a generous offer but I'm probably not going to tackle this until after the season is over. I'm in MoCo about 30 miles west of Baltimore so probably too far to be feasible anyway. Even though it's only an hour or two of labor it's really a 2 day job considering the cure time for the epoxy and gel coat.
My biggest concern is getting those holes right. Do you think the method I describe will work?

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Taking the motor off completely is not necessary. I already had it off the second time and it is easier to drill and patch that way.
The first time, on the 1964 I ran a 2x12 from a beam in my carport to the top of a 6' stepladder in line with the top of the motor. Then used a cable puller to secure the motor. When it was tight I removed the bottom lag bolts.

Then I removed one top bolt and loosened the other so the motor could pivot on the one remaining bolt. I was able to re-insert the other top bolt one hole up at that point. Then I pulled the other top bolt and pivoted the motor to raise the second top bolt one hole. Repeated this process to raise the motor to the third hole up.

Then with the top bolts re-inserted I was able to drill the green holes with the motor in place. Slight upward angle was necessary to get holes into the splash well. It was a while ago, but as I recall the lag holes were below the motor bracket after the motor was raised.
Epoxy thickened with fine chopped glass, or a dowel and epoxy will fill the holes. I used "wet /dry 700" a fairing epoxy compound from Progressive Epoxy the second time. It is super easy to work with and doesn't run at all.

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ok, so I remounted the engine 3 holes up, and i'm still getting around the same performance. i'm only seeing a top speed of 36 mph on the gps. my tach isn't currently working so I cant tell what rpms it's spinning. I do have a new tach on the way. I pretty sure the prop I have is wrong. I currently have a 13 1/4x17 solas new Saturn prop. the hole shot is good and the midrange is good, but top end isn't what it should be. the motor is healthy. i'm willing to sacrifice some hole shot and midrange for top end speed. the stiletto advantage is no longer available. which prop should I get?

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Don't do anything till you get a tach. You are blind without it.

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Ok, so I got the tach working and I'm hitting 36 mph at wot at 45-4600 Rpms. If I trim up high it revs a little more and begins to porpoise.

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Your rpm's sound low. Can you tell us what your engine operators manual indicates the acceptable operating rpm range is?

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It should be close to 5500 rpms at wot according to everything I've been reading. I'm pretty sure I need to go down in propeller pitch.

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Thank you mtown for the detailed explanation but with my current install I'm pretty sure I will need to remove my engine to fill the bottom holes (1989 Montauk with 1998, 90 hp Yamaha 2 stroke). I have some time this weekend and I'm pretty sure I can do it in my garage with a little engineering.

I'll post a picture later but the bottom mounting on my current engine is a slot as opposed to the top mounting which is 4 holes. Can anyone tell me if the new engines have the same configuration?

If the bottom mounting on new engines is now a 4 hole configuration instead of the slot it adds another level of complexity to make sure I get the bottom holes at the perfect height.

My second minor concern is I estimate the current blind hole is very close to where I will need to drill the new hole. I realize if the hole is filled properly it shouldn't matter but it makes me nervous that the drill bit could drift if they do overlap and I'm boring through two different materials.

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The bottom is still a slot. My 2007 Yamaha 2-stroke is mounted 3 holes up and the bottom bolt is near the top of the slot. It was mentioned on this thread or another that you can drill the bottom holes after raising the motor and attaching with the top bolts. I did that on this boat and it works. With the motor completely off, I would use the measurements given by Joe and drill the green holes. That is what I did on my other 16' and it worked fine also.

Your splash well is probably deeper than mine but you may have to angle the drill bit slightly upward when you drill. Others with a Montauk of similar age could tell you for sure, or just measure down from the transom notch.

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Thanks again mtown. I started getting it prepped last night and should be done soon. My splash well is deeper then the older Montauks so no issues there.

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Aside from being nominated for the next Darwin award for the way I jacked up my engine... the other concern I had was what I'd find inside the transom. Turns out the top holes were solid and dry but the blind holes were moist inside but the wood is very solid. Not great but sort of to be expected after 17 years since it was installed and if left unchecked it could have lead to more serious issues down the road.

I put a 100w lightbulb outside each blind hole and aimed a small blower / heater in the splash well for now. Hopefully it'll be dry enough by later today so I can get back to it but I'll wait add long as needed.

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Many epoxies will set up in moist or even wet conditions. Progressive epoxy sells a lo-vis epoxy that will set up on a glass of water. Probably West has a similar product. Progressive's wet/dry 700 epoxy putty can also be installed underwater and is much easier to work with. About half way between mayonnaise and peanut butter.

You will only need a small amount. I have half of my gallon kit in my basement. I would be happy to donate some to your repair. e-mail me if interested.

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Jax -

Before messing with the prop, ensure the throttle linkage is properly set so that with the binnacle throttle all the way forward, the link in the engine is at the stop.

If you are 3 holes up, light load and only hitting 4600, you have the wrong prop.

Having had the exact setup myself, I say go with the Yamaha painted stainless steel or Stiletto. Not a fan of Solas. Remember blade design is different across brands, so an X by Y from Yamaha is not the same as an X by Y from Stiletto.

Yamaha and Stiletto Advantage props work well with Yamaha motors on classic 16 an and Montauk hulls.

With the engine 3 holes up, motor in tune and a good prop, you should see 42-43 mph @5500 rpm with full load of fuel, no gear and just you.

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Thanks Phil. That's what I was expecting. The prop that I had on my old 70 Yamaha 2 stroke was the Yamaha 13x17k prop. Is this the same as the Yamaha painted prop? I'm going to try this prop and see if I get anything different. I know this motor has more. It's just not revving like my 70 was. And I actually saw 35-36 top speed with my old 70. I know this 90 should be at minimum above that. Not maxing out at that.

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Jax,
Which holes did you drill in this drawing below?
http://www.whalercentral.com/articles...icle_id=82

For the Montauk 17' hulls (and other 17' models) about 1986 a later, you should be able to drill the "Red" holes as Boston Whaler changed the depth of the splashwell for this reason.
As Always, layout the holes first on both the inside and outside of the transom to make sure the washers do not interfere with the radius at the bottom of the splashwell.

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Mtown, thankfully the holes were dry today so I'll glass them tomorrow with west systems epoxy and chopped glass so I'm good to go.

I had my drain tubes replaced about 10 years ago and they're still in good shape but the guy that did the job said the bottom one was wet. After this adventure I think I'll pull them at the end of the season and let it dry in the garage over the winter.

I'm not expecting much in terms of performance improvement but I'll post my results as soon as possible.

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Jax. I have a 13.25 x 15 Stiletto Advantage 1 for sale. I used it for about 40 hours on my F70 before moving to a different prop; the Advantage is in absolutely perfect condition - not a single scratch or ding or nick on it. It also has the correct Yamaha hubkit for your application.

If you are interested, please PM or email me.

Tim

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well, I decided to try the old prop from my 70hp on the 90hp motor and there was a noticeable difference in rpms. the prop that was on my 70hp is a 13x17 prop also. I believe it was a Yamaha prop because it has 13X17K stamped on it. is this indicative of a Yamaha prop? with the old prop my rpms went up to 5k and the top speed was 38 mph at wot. I had a decent load in the boat and 20 gallons of fuel.

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The Yamaha 2-stroke 90 and the Evinrude E-tec 90 are very similar in actual HP at the prop, and should run neck and neck. They do not use the same prop, however, since they have different gear ratios. Both usually give 40 MPH, maybe a little better, on a classic Montauk. It should also be noted that the prior 16' hulls are lighter and run faster with the same HP, so they are not a good comparison.

Both the Yamaha 90 and Mercury 90 2-strokes use a 2.33 gear ratio. When Whaler was selling these boats factory rigged with Mercury 90 2-strokes, the furnished prop was either a Mercury Black Max aluminum 21" pitch, or a Laser II 20" pitch. So the Yamaha maybe should be able to turn a 19" pitch prop at least, since I do believe the Merc puts out more power than the Yamaha. I don't think the Yamaha 90 can turn a 21" pitch prop like the Merc does.

With the engine raised up, and putting out the rated HP, the fastest prop you can buy for that rig would be a Mercury Laser II in 19" pitch. They give tremendous hull lift and top speed on a Montauk, and are faster than a Stiletto on an actual pitch for pitch basis. If your engine can't turn anybody's 19" prop raised up (or a 17" Stiletto), the engine should be looked at. Sometimes used engines can look nice cosmetically, but are worn out internally.

You appear to be only getting 70 HP out of it.

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Joe ,my motor is now mounted two holes up, which is the third hole down in the upper set of holes, the bottom bolts are in the slots and I can adjust by raising the motor even further up to the lowest hole in the upper set of holes. Everything that I've read has said that the 13x17 pitch prop is the correct size. Not sure where a 19 pitch came from,but with my old 13x17k prop, 38 mph seems about right given my load and the water not being glassy. I would probably see 40 with lighter load and smooth water.