Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Optimizing the performance of Boston Whaler boats
Lean Wolf
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Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Postby Lean Wolf » Sun Nov 27, 2016 7:42 pm

I recently purchased a 1998 OUTRAGE 17 II with a Honda BF115. I've only put about two hours on the boat, and I have found the boat to porpoise significantly.

To anyone who has [a 1998 OUTRAGE 17 II with a Honda BF115] and [who has problems with the repeated oscillation of the bow up and down]: what have you done to reduce [the repeated oscillation of the bow up and down]?

[On my boat] the propeller is chewed up; I need to start there.

To anyone who has [a 1998 OUTRAGE 17 II with a Honda BF115] and [has problems with the repeated oscillation of the bow up and down]: What propeller are you using?

I have a lot of experience with high-performance propellers but no experience dealing with [the unidentified and chewed up propeller that is on this] 17-foot Boston Whaler.

[Describes the engine mounting height by describing the hole the mounting bolts has been placed in--please describe the engine mounting height in terms or units of 0.75-inch or "hole" that the engine has been raised above the lowest position. For more help in describing the engine mounting height see the article at http://continuouswave.com/forum/viewtopic.php?f=7&t=739]

To anyone who has effectively dealt with [the tendency of a 1998 OUTRAGE 17 II with a Honda BF115 to have the bow oscillate up and down while the boat is on plane]:

What did you do to stop [the tendency of a 1998 OUTRAGE 17 II with a Honda BF115 to have the bow oscillate up and down while the boat is on plane]?

What is your propeller?

What is your engine mounting height?

Advice would be sincerely appreciated.

jimh
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Re: Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Postby jimh » Sun Nov 27, 2016 8:00 pm

What is the weight of the Honda BF115 engine on your boat?

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Phil T
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Re: Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Postby Phil T » Mon Nov 28, 2016 12:35 pm

Lean--porpoising can be exacerbated by many conditions, including:

--engine mounted too low
--incorrect propeller
--inadequate application of engine trim
--stern weight bias
--sea state
--wind conditions.

A typical engine mounting height for a Boston Whaler hull is 2 or 3 holes up.

I did a search of the archives and there are few members running a BF 115 motor. If you don't get any suggestions here, I recommend contacting Ken @ Prop Gods. He has helped dozens of whaler owners find the right propeller. You should mention that 115 is on the low end of the power band for that model.

http://www.propgods.com/Content2/Default.aspx

I would double check engine height and adjust as necessary, replace prop and retest. Report results and we' can go from there.
1992 Outrage 17
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Ridge Runner
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Re: Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Postby Ridge Runner » Mon Nov 28, 2016 3:35 pm

As Phil mentions the 17 foot Outrage II is prone to porpoising. Most [of these] boats were sold with either a Mercury 125-HP or Mercury 150-HP two-cycle outboard engines with a weight of 350 to 400-lbs. Your Honda BF115 has added about 100-lbs to the stern of the Outrage II. I owned an 17 foot Outrage II with a Mercury 125ELPTO; it performed well.

When I sold the boat, the new owner re-powered with a heaver Yamaha F115 at just under 500-lbs. The new owner experienced most of the same operating characteristics that you have described. Moving any weight you can from the stern will help.

Also, check your propeller as Phil has noted. You need to use a stern lifting propeller with this set-up any propeller that is bow lifting will really extenuate the porpoising condition. Ken at Prop Gods is a very good resource.
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Lean Wolf
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Re: Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Postby Lean Wolf » Mon Nov 28, 2016 10:14 pm

Thank you for your replies. I believe the engine weighs 485-lbs.

I really don't have any weight I can move forward with the exception of re-mounting the battery farther forward in the console; everything else is already in the bow storage area.

The propeller is a Honda 13.5 x 15.

I have to read the details around the engine mounting height in terms of inches however right now it is set as two [holes] up. When I trim out the [engine] from the trim being all the way down, I can count to two seconds and that's where [the boat] wants to run. At three seconds [the engine] seems too high and the oscillating is more prevalent. This tells me that the engine mounting may be too high on the boat and I may want to lower it by one hole to bring the bow down. Does this logic makes sense? Thanks again.

Ridge Runner
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Re: Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Postby Ridge Runner » Tue Nov 29, 2016 3:38 am

Is your Honda 13.5 x 15 propeller a stainless steel prop? PN# 58133-ZY3-A15S a Solas Titan (Solas manufactures Honda propellers)? If so this is a high rake blade design that provides bow lift.

If you want to stay with Honda (Solas) propellers I would look at trying their HR Titan 4 Propeller, this is a stainless steel 4 blade prop that is noted by Solas as "having great stern lift". For a 4 blade stainless steel propeller it is very nicely priced ~$250 retail: http://www.boatownersworld.com/solas-hr ... pline.html

A stern lifting propeller will push your bow down and help control the porpoising. A 4 blade propeller will give you good acceleration and excellent mid-range control, you will loose a MPH or two at the top end and slightly reduce the operating efficiencies. Depending on your current RPM operating range I would look at the 13.25" x 15" or the 13.5" x 13" HR Titan 4.
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2005 170 Montauk, 2010 E-TEC 115 H.O.
2016 210 Montauk, 2017 E-TEC G2 200 H.O.

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flymo
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Re: Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Postby flymo » Tue Nov 29, 2016 11:32 pm

No, lowering the motor does not make sense. In general, lowering the motor will tend to lift the bow more and make porpoising worse. Think of the prop as being at the end of a lever, pushing the bow up. Longer lever means more lift.

Try raising the motor that last hole and get a good stern lifting propeller. I think you will see some improvement. Visualize it as lifting the whole boat and skimming across the top of the water with the boat relatively flat, as opposed to having the stern deeper in the water and the bow up.

In your situation, with significantly less than the maximum power on the transom, I would be disinclined to go with a four-blade propeller. They are generally best when you have plenty of power and are looking for more grip on the water.

I had good luck getting in touch with PowerTech propellers. If you go to their website (http://www.ptprop.com/) and click on the Contact Us banner tab, then the Prop Worksheet in the right margin, you can enter all the information about your situation in the form, send it in, and they'll get in touch. They got back to me in less than 24-hours just before a holiday weekend, and were apologetic that it took them so long. And after some additional e-mail discussion to clarify what I was looking for, their recommendation was spot on.

Good luck with it.

Flymo

jimh
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Re: Outrage17 II and Honda BF115: Repeated Oscillation of the Bow Up and Down

Postby jimh » Thu Dec 01, 2016 2:25 pm

If the engine is mounted two-holes up, I'd leave it there. Experiment with a different propeller. Since the present propeller is described as "chewed up", almost any new propeller with blades that are not chewed-up will be likely to work better.

Just about any small outboard-powered boat can be driven into repeated oscillation of the bow up and down while on plane if the engine trim is not carefully adjusted. I can get my boat to porpoise at certain boat speeds and trim, too. To stop it, I just change the engine trim.