190 Nantucket 135 OptiMax

Optimizing the performance of Boston Whaler boats
roundle1979
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190 Nantucket 135 OptiMax

Postby roundle1979 » Tue Jul 14, 2020 11:27 am

I have a 2004 [190] Nantucket with the original Mercury OptiMax 135-HP engine.

The boat came with two propellers:
—a Mercury MIRAGEplus part 48-18278 with PVS option; the PVS holes are filled with solid plugs; and
—a QuickSilver Mirage (#48 13700 A41 19P) which I have never tried.

When I have the boat loaded with family, I tend to accelerate more gently and travel below 25 MPH. If I get up on plane gently, I get what feels like excessive ventilation until I hit about 20 MPH, when suddenly the RPMs drop and the engine quiets down a bit.

It also feels like a slipping clutch. I find it annoying and sort of unpredictable.

I want to eliminate this ventilation. Where should I start?

What additional details would this forum find helpful?

macfam
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Re: “slipping clutch”

Postby macfam » Tue Jul 14, 2020 12:37 pm

That ”slipping clutch” you describe maybe a slipping prop hub.

Is the Pitch on the spare Quicksilver Mirage close to the prop your using? If yes, give it a try to see if the problem subsides.

roundle1979
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Propeller part number

Postby roundle1979 » Fri Jul 17, 2020 10:06 am

The current propeller is a part number 48-18278. 17P

jimh
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Re: 190 Nantucket 135 OptiMax

Postby jimh » Fri Jul 17, 2020 8:14 pm

A MIRAGEplus propeller will use a FLO-TORQ hub. Inspect the plastic hub bushing.

roundle1979
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Re: 190 Nantucket 135 OptiMax

Postby roundle1979 » Sat Jul 18, 2020 9:32 am

Photos of current propeller.
Attachments
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IMG_1288.jpg (45.42 KiB) Viewed 1921 times
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IMG_1287.jpg (65.71 KiB) Viewed 1921 times

jimh
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Re: 190 Nantucket 135 OptiMax

Postby jimh » Sun Jul 19, 2020 8:53 am

Have you inspected the propeller and hub for indications of the hub slipping?

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Re: 190 Nantucket 135 OptiMax

Postby jimh » Mon Jul 20, 2020 2:33 pm

You cannot detect a slipping hub by looking at three pictures of the propeller posted above.

The best view to establish the propeller was a Mercury MIRAGEplus would be to show that name embossed into the propeller. Most readers don’t have a cross reference to Mercury part numbers.

There does not appear to be any blade damage shown in the picture that shows the blades. Damage would have to be very major to show up in a picture.

The 17-pitch MIRAGEplus is a large diameter propeller. This means the blade tips will be close to the anti-ventilation (A-V) plate. The MIRAGEplus may not tolerate being run with the A-V plate running out of the water.

What is the engine mounting height in units of holes above lowest position?

ASIDE: I have been using a MIRAGEplus 17-pitch for many years and it has never ventilated—even running in very rough seas.

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Re: 190 Nantucket 135 OptiMax

Postby biggiefl » Mon Jul 20, 2020 2:50 pm

To see if it is slipping you need to mark the hub and the prop, take it for a ride, let it slip and then look at the marks. If they have moved, need a new hub. You would mark it in pic 3. Mark the metal prop and part of the hub if you can see it(should). I use an awl or nail to just scratch it.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

roundle1979
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Re: 190 Nantucket 135 OptiMax

Postby roundle1979 » Tue Dec 01, 2020 3:46 pm

My propeller is a Mercury MIRAGEplus; it uses a Flo-Torq II hub. The prop is a 15-1/2” x 17”, part # 48-18278. I believe that this is the factory propeller that came with the boat back in 2004

The problem is not with the hub, it is simply ventilating. Here are my observations

  • A number of other Boston Whaler Nantucket or Outrage 190 owners have reported similar traction problems with [a MIRAGEplus propeller]. The ventilation is mostly a problem in rough and choppy waters.
  • One of the reasons the current propeller is ventilating may be related to the fact that the motor is mounted quite high from the factory, which works for a prop like the Enertia, but not for the MIRAGEplus.
  • My MIRAGEplus propeller has some non-factory stampings. This propeller likely been repaired in the past by the previous owner; it's likely no longer in-line with the factory specifications

I will next try both an ENERTIA 17 and a REVOLUTION4 in 17-pitch. I am leaning towards the REVOLUTION4 as the stern lift may be helpful when I'm forced to reduce speed in choppy water.

roundle1979
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Re: 190 Nantucket 135 OptiMax

Postby roundle1979 » Tue Dec 01, 2020 3:51 pm

Detailed example of the type of ventilation I experienced this season:

In late July I took a trip from Milton Harbor (Rye, NY) to Oyster Bay (Long Island, NY). Great day on the water.

When we left in the morning, it was calm. 40 gallons of fuel, two adults and 3 kids. No ventilation to speak of on the trip over. We spent a few hours at the beach at Oyster Bay. Before returning, we filled the tank (added 20 gallons, so a full 60 gallons). The winds speed increased to greater than 15-MPH in the afternoon, and there was more large boat traffic, so Long Island Sound had become choppy. Ventilation on the way home was noticeable and quite annoying as I was constantly adjusting speed (between 12 and 22 MPH) to ensure a safe and comfortable ride of my passengers.

Seems as though Whaler dialed this boat in for a lake rather than a snotty day on Long Island Sound.

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Phil T
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Re: 190 Nantucket 135 OptiMax

Postby Phil T » Tue Dec 01, 2020 4:55 pm

You are correct, the Mirage is the original factory prop.

I think part of the concern is your acceleration technique.

I tend to accelerate more gently


Consider this:

When loaded you have more weight to get up and out of the water. While 2 strokes have a better torque curve than a 4 stroke accelerating slowly makes it hard for the engine and prop, especially in waves. I would accelerate to 4-7 mph and then accelerate very quickly till you are just on plane, then reduce throttle quickly before you gain too much speed.

With practice, it will not feel jerky to passengers.
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biggiefl
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Re: 190 Nantucket 135 OptiMax

Postby biggiefl » Wed Dec 02, 2020 11:03 am

No boat likes to get on plane gradually, a prop is not going to solve your ventilation. You need to goose it and get on plane then slow down and trim up.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

roundle1979
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Re: 190 Nantucket 135 OptiMax

Postby roundle1979 » Thu Dec 03, 2020 11:35 am

Spoke to Ken at https://propgods.com/.

Rev4 in the mail.

Looking forward to May.

fno
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Re: 190 Nantucket 135 OptiMax

Postby fno » Thu Dec 03, 2020 11:31 pm

Good luck with the REVOLUTION4 propeller.

If that doesn't work I think you should describe the height of the motor on the transom in "holes up" or provide a photo of the anti ventilation plate and it's relation to the keel of the boat. There are many here with the experience and know how. They just need the right information.

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Re: 190 Nantucket 135 OptiMax

Postby jimh » Fri Dec 04, 2020 6:39 am

The REVOLUTION4 propeller is probably too much blade area and too much weight for a 135-HP engine. If you want to try it, I recommend you do so on the basis that you can return the propeller for credit if you find it unsuited. I have tested a REVOLUTION4 17-pitch propeller, but I found in unsuited for my 225-HP engine. A 15-pitch MIRAGEplus would have been more suited, but at the time of testing there was no 15-pitch version available to try because Mercury was not making any in that pitch.

The propeller you describe as a MIRAGEplus lacks the normal markings found on a MIRAGEplus propeller. Usually the name MIRAGEplus is cast into the propeller hub and clearly identifies the propeller model.

In my own experience with the MIRAGEplus propeller I have not had a single problem with the propeller ventilating and subsequently losing thrust. I have operated in some very rough seas and the MIRAGEplus has never blown out or shown any sign of ventilating. And my engine mounting height is quite elevated compared to most installation. The engine is mounted one-hole-up on a Whaler Drive, which is probably a higher engine mounting than two-holes-up on a notched transom.

roundle1979
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Re: 190 Nantucket 135 OptiMax

Postby roundle1979 » Fri Dec 04, 2020 9:37 am

jimh wrote:The propeller you describe as a MIRAGEplus lacks the normal markings found on a MIRAGEplus propeller. Usually the name MIRAGEplus is cast into the propeller hub and clearly identifies the propeller model..


Hi Jim--My prop was indeed one point a MiragePlus (it's clearly stamped); however, the additional markings/stampings indicate that it's been worked on in the past. While it may sound like I am complaining about the MiragePlus in reality I am just complaining about MY (old , corrected) MiragePlus.

Photos of my prop:

*Branding: https://cimg5.ibsrv.net/gimg/www.thehulltruth.com-vbulletin/2000x1504/img_1291_5576d5ed2aa3bfe3f37c1d49b1d4e5addcb5dd5c.jpg
*Model number: https://cimg3.ibsrv.net/gimg/www.thehulltruth.com-vbulletin/2000x1504/img_1289_f1be2cbb4e5194642c99679b2798b06732fe52a1.jpg
*Non factory stamping (from repair work): https://cimg4.ibsrv.net/gimg/www.thehulltruth.com-vbulletin/2000x1504/img_1290_136e50e8e6e1bf88c8c03a199f462c761f019ab6.jpg

I have ordered the [REVOUTION4 17-pitch propeller] through https://propgods.com; if I want to exchange it I can do so for $35. Ken seemed to think it was probably the right application based on my requirements. I realize that I may gain some low speed performance at the cost of a few top end MPH.
In any event, I'll try the REVOLUTION4 and report back in May.
Last edited by roundle1979 on Fri Dec 04, 2020 10:13 am, edited 1 time in total.

roundle1979
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Re: 190 Nantucket 135 OptiMax

Postby roundle1979 » Fri Dec 04, 2020 9:40 am

fno wrote:Good luck with the REVOLUTION4 propeller.

If that doesn't work I think you should describe the height of the motor on the transom in "holes up" or provide a photo of the anti ventilation plate and it's relation to the keel of the boat. There are many here with the experience and know how. They just need the right information.


The engine was mounted by the Boston Whaler factory: Here's a high res photo (not supported by this website):

https://cimg3.ibsrv.net/gimg/www.thehulltruth.com-vbulletin/2000x1504/img_0962_01e66d4bac0e0f29f56dea08854fd31ad36203a8.jpg

jimh
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Re: 190 Nantucket 135 OptiMax

Postby jimh » Fri Dec 04, 2020 10:26 am

[exturl]n[/exturl]


ROUNDLE--your reply has me laughing. Let me explain several things to your about photo images and this website.

First, you want READERS to see a photo and from the photo the READERS are to deduce the engine mounting height. This is really a bit awkward method, because you could just TELL US the engine mounting height. But maybe you can't figure out the engine mounting height yourself, and that's okay, we can figure it out from a photo.

The second problem is your claim that the photo is not unable to be made an in-line photo because of its "resolution." The image resolution has nothing to do with this. The image was rejected because either it exceeds the maximum image size, or it exceeds the maximum file size.

In fact, to show us the engine mount details by providing a picture is entirely possible. We just need a picture that just shows the engine mounting area, not the whole boat, the backyard, the sky, the ground, ladders, and other boats. So there is NOTHING preventing you from posting an inline image of the engine mounting. In fact, I will crop off all the other parts of the "high-resolution" image you want READERS to interpret and include it right now:

engineOrig.jpg
Fig. 1. The original image, cropped to show the engine mount only.
engineOrig.jpg (3.77 KiB) Viewed 1031 times


Now we have the third problem: the image exposure and contrast prevents seeing much about the engine mounting height. I tried to see more from the image by making some exposure corrections:

engine.jpg
Fig. 2. Image with exposure correction.
engine.jpg (4.78 KiB) Viewed 1031 times


Now we have the fourth problem: the mounting height is still not clearly seen. It might be--guessing--mounting one-hole-up

Please go back to the boat and take an actual high-resolution image of the engine mount with good lighting and proper exposure. Then crop the image so it is smaller than 900 x 900 pixels, and, if the image shows some detail that is usable, you are welcome to include it as an in-line image, or just as useful, host it where you hosted the other image. But please don't imply that there is something about the forum's limit on in-line image size or file attachment size that is impeding the announcement of the engine mounting height on your boat in this discussion.

jimh
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Re: 190 Nantucket 135 OptiMax

Postby jimh » Fri Dec 04, 2020 10:37 am

I see in your more recent images of the propeller that the brand and model are clearly identified. Here is a cropped and re-oriented version of the original.
propeller.jpg
Fig. 3. Photo of propeller under discussion; rotated 90-degrees and then flipped 180-degrees so the cast-in text is reading left to right and right-side up.
propeller.jpg (11.29 KiB) Viewed 1026 times


Yes, it is clearly a Mercury MIRAGEplus propeller.

You have inferred that some propeller shop has worked on the propeller based on some stamped numbers. That might be very true. But the notion that because a propeller shop worked on the propeller it is no long in specification is not an intrinsic outcome. The MIRAGEplus propeller is just a standard line propeller from Mercury, and perhaps the propeller was sent to a shop for custom balancing or other work. Or the pitch might have been slightly altered. There is no telling exactly what was done. From all the images you have provided, I don't see anything unusual.

Another variation in performance: propellers might work differently on different engines due to the design of the gear case. When I bought my MIRAGEplus propeller, initially testing was a bit disappointing, and my notes mention some ventilation or loss of grip. However, when I changed engines on my boat and put the same propeller on a different engine with a different gear case, I was completely pleased with its performance and there has never been any ventilation. In my case neither engine was Mercury. You'd think a Mercury propeller on a Mercury gear case would work in an optimum manner. And apparently Boston Whaler thought so, too.

roundle1979
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Re: 190 Nantucket 135 OptiMax

Postby roundle1979 » Fri Dec 04, 2020 2:47 pm

jimh wrote:
roundle1979 wrote:ROUNDLE--your reply has me laughing.

Glad I'm able to provide some entertainment.

Attaching a couple more photos:

Photo 1: This should highlight that [the engine is mounted two-holesup].
IMG_1833.jpg
IMG_1833.jpg (67.81 KiB) Viewed 997 times


Photo 2: The cavitation plate shown relative to the bottom of the hull. Note that the engine is trimmed all the way down so the cavitation plate is not parallel, but this should give you a good idea of the engine height.
IMG_1832.jpg
IMG_1832.jpg (150.97 KiB) Viewed 997 times

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Re: 190 Nantucket 135 OptiMax

Postby jimh » Fri Dec 04, 2020 6:44 pm

The engine mounting height as seen above is two-holes-up, or 1.5-inches higher than the lowest mounting height. The photo image that illustrates this is very clear—making the photo perfect for illustration.

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Re: 190 Nantucket 135 OptiMax

Postby Phil T » Fri Dec 04, 2020 8:44 pm

I would say to an owner who posted just this photo, the engine should be raised so the anti-cavitation plate is 1-2" above the bottom of the keel.

As shown, the current height appears to be less than 1/2".
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roundle1979
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Re: 190 Nantucket 135 OptiMax

Postby roundle1979 » Mon Dec 14, 2020 8:24 pm

An older post describes propeller ventilation from a MIRAGEplus—coincidentally on an Outrage 190, the same hull as my boat.

http://continuouswave.com/ubb/Forum4/HTML/005861.html

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Re: 190 Nantucket 135 OptiMax

Postby jimh » Thu Dec 17, 2020 11:31 pm

Propeller ventilation can be affected by many influences. An influence often overlooked is the outboard engine itself. I will give an example from my own experience.

I was using a particular propeller with my boat when the engine was a classic carburetor 225-HP two-stroke-power-cycle engine with no electronic controls. Engine speed was determined principally by throttle setting of the carburetor butterflies, the fuel jet orifice sizes, and the spark advance. The spark advance mechanically connected to the throttle movement, so spark timing changed. Once the throttle was opened to a particular setting, the engine speed would then be determined almost entirely by the load on the engine. This behavior is common on classic two-stroke-power-cycle engines with carburetors and no modern computerized control module.

With the engine as I described above, the particular propeller showed a tendency to lose grip or ventilate in rough seas.

Later, after an engine change and on the same boat, the same propeller showed no sign of ventilating. The new engine was a modern engine with sophisticated electronic engine controls, and individual cylinders fed fuel by direct injection. The behavior of this engine at higher throttle settings is quite different than the earlier engine. With the modern control system, this engine tends to run at the speed you set the throttle, and not vary much with small changes in load. I believe this behavior affects how the propeller performs.

With the older engine, any reduction in propeller load, as might occur with some initial propeller ventilation, would result in an immediate increase in engine speed in response to the reduced load. The increase in engine speed would then tend to cause more ventilation. More ventilation would reduce engine load further, causing more engine speed increase. This cycle would rapidly lead to the propeller losing grip and ventilating. To stop the cycle the throttle would need to be reduced, reducing engine speed, until the ventilation stopped. As soon as the ventilation stopped, the propeller would begin to get more grip, thus increasing the engine load. The increased engine load would reduce engine speed, requiring the helmsman to increase throttle.

The new engine behaves much differently. If the throttle is set for, say 3,700-RPM, the engine tends to run at that speed and will not suddenly increase or decrease speed if the load from the propeller suddenly is reduced or increased. The engine exhibits a great deal or reserve power while also not exhibiting a tendency to jump up in engine speed the moment the propeller load decrease. The result is that if some ventilation begins, the engine does not immediate respond with an engine speed increase. The result is that the ventilation does not increase. If in the next few seconds the propeller is more deeply immersed, as occurs when the boat is operating in rough seas, the propeller regains grip.

The overall all effect is that the same propeller behaves quite differently with two different engines, depending on the type of engine speed control system that is used in those engines.

The particular propeller I have used when observing this behavior was a Mercury MIRAGEplus. I was not particularly impressed with the propeller's ability to avoid ventilating with the old engine, but with a change in engines the propeller lost all tendency to ventilate.

I believe the engine affects the propeller's tendency to ventilate based on how well the speed of the engine is controlled.

The combination of the engine speed remaining steady and the propeller not ventilating creates the ability to run the boat at a nearly constant speed in heavy seas without constant adjustment of the throttle. This greatly reduces the burden on the helmsman when steering in rough seas. The helmsman can concentrate on steering the boat, avoiding really big waves, and he does not have to keep one hand on the throttle at all times to pull back if the engine speed begins to increase due to onset of ventilation.