1992 Outrage 17 Re-power Yamaha F90 or F115

Optimizing the performance of Boston Whaler boats
Dev
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1992 Outrage 17 Re-power Yamaha F90 or F115

Postby Dev » Wed Jan 27, 2021 12:11 pm

I have a 1992 Outrage 17 that I would like to re-power. I am concerned about horsepower-to-weight tradeoff.

The boat currently has a Johnson 120-HP two-stroke-power-cycle engine that (I think) weighs 365-lbs and is likely the 1992 OUTRAGE 17 boat's original engine.

The 1992 OUTRAGE 17 boat has dual batteries located in the console and an internal 32-gallon fuel tank.

The 1992 OUTRAGE 17 boat performs very well as currently set up. It is fast and dry, but I have noticed that the two cockpit drain outlets are slightly below the waterline when the engine is idling , and I have to plug them.

I am not sure if this [static trim on the boat] the way the hull was designed, or if this static trim is an indication that the engine is slightly too heavy for the boat.

The maximum horsepower for the 1992 OUTRAGE 17 is 120-HP, so [the present 120-HP engine] should not be a problem.

I'm considering re-powering with either a Yamaha [F]90 (353-lbs) or Yamaha [F]115 (377-lbs).

With the Yamaha [F]90, I'm concerned about the boat being under-powered, especially with two or three people aboard and a full fuel tank.

I'm pretty sure with the Yamaha [F]115 that [loading of the boat] that wouldn't be a problem, but worry I may be adding, if only slightly, to an existing weight problem.

Q1: [Between the Yamaha F90 and the Yamaha F115) which engine should I use for re-powering the 1992 OUTRAGE 17 boat?

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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby jimh » Wed Jan 27, 2021 1:36 pm

I am unclear what you mean by a trade-off of horsepower-to-weight trade-off. I think more horsepower will always tend to include more weight. The question is: how much more horsepower for the added weight of a more powerful engine.

In the case of the two engines you cited: I presume you are asking about Yamaha four-stroke-power-cycle engines with model designators F90 and F115. You should clearly identify the engines you want to discuss with their specific model designators.

Regarding the engine weight and its effect on horsepower-to-weight ratio: the increase to 115-HP from 90-HP gives 25-HP more with only an increase in weight of 24-lbs.This is a horsepower-to-weight ratio of 1:1--an extraordinarily good ratio.

The performance of the boat is related to the total horsepower-to-weight ratio for the boat, not just for the engine itself. Considering the total boat weight is probably about 2,400-lbs, getting 27-percent power increase (to 115-HP from 90-HP) for only a 24-lbs or one-percent increase in total weight seems like an extremely good way to add horsepower without imposing much weight increase.

Q2: Regarding the static trim on the boat with the present engine and the cockpit drain outlets being at or just below the waterline: are you referring to the engine splash well drain?

Generally the location of the engine splash well drains relative to the static waterline (when the boat is NOT underway) will be an indicator of the boat's trim and total hull weight loading.

If you are concerned about increasing engine weight by 25-lbs with the F115 engine instead of the 90-HP engine, you can easily simulate the weight change with temporary weight placed onto the existing engine. Only 17-lbs would be added to the current engine to simulate the weight of the F115. This is a miniscule difference in total boat weight, and I doubt it would produce any easily measured difference in the hull trim. The boat only needs to displace 17-lbs more water to create the necessary buoyant force to resist the added 17-lbs.

The density of seawater is about 64-lbs per cubic foot so the volume of water needed to be displaced is going to be 17/64 or 0.26-cubic feet. Assuming for a moment the hull form is a box that is 7-feet wide and 10-feet long, to create added buoyancy means the hull will submerge a farther 0.26/70 feet, or 0.0038-feet or 4/100th of an inch into the water.

Dev wrote:Q1: [Between the Yamaha F90 and the Yamaha F115) which engine should I use for re-powering the 1992 OUTRAGE 17 boat?

A1: if you want to maintain the boat's current performance you should get the Yamaha F115 engine.

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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby biggiefl » Wed Jan 27, 2021 1:45 pm

There are many reasons why PERKO and others make drain plugs.

Most Boston Whaler boats do not self drain and require a plug (or more) while at rest. Some use [check-valves on the] scuppers so that they do not need to use plugs. Many have good results with [check valves on scuppers] but they are not the answer if a lot of weight is in the stern as when fishing or carrying a live well.

I would not be concerned about 24-lbs--it is easily counterweighted with some lead in the anchor locker.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

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Phil T
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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby Phil T » Wed Jan 27, 2021 2:21 pm

DEV--I owned a 1991 Outrage 17 for more than seven years with a F115, and I now own a 1992 model with its original Evinrude 115 two-stroke-power-cycle engine.

I did extensive research in preparation of the re-power and regularly talked to many Outrage 17 owners here and abroad. If you search this forum and the archives, you can read many of my posts concerning the weight sensitivity of this particular model. I do not recommend engine weight over 370-lbs. I ran with all the drains closed and the splashwell was half-full at rest with the F115--not good.

My 1992 is in the middle of a re-power and restoration with an E-TEC 90-HP engine waiting to be installed. I selected the E-TEC 90-HP for the weight advantage.

Unless you are pulling a slalom skier, doing long distance, or high speed runs, a 90-HP engine is only 5-MPH slower at WOT, about 42-MPH versus 46-MPH.

If you are looking for low-end acceleration, consider the recently introduced Yamaha I-4 V MAX SHO 90 or 115 models. They have the same weights as the F90/F115.
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Dev
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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby Dev » Fri Jan 29, 2021 1:38 pm

Thanks, all. Phil, in an earlier post I saw you had recommended a maximum engine weight of 400 pounds. Is your current recommended limit of 370 pounds based on additional experience? I must admit I am leaning slightly toward the F115, but am impressed with the fact that, given your experience with the Outrage 17, you are repowering with an ETC 90.

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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby Phil T » Fri Jan 29, 2021 2:30 pm

Thoughts that pushed me to a 90hp engine rather than a 115hp engine to repower my Outrage 17.

  • The weight difference was significant.
  • During my 7 year ownership of the 1991 model, I spent a great deal of time and effort avoiding shipping water in the boat due to the stern bias of a 405-lbs-engine. Fellow Outrage 17 owners with a F115 or other 400-lbs engines did not have as much trouble as I did, but they were not operating in similar conditions. I frequently was underway in Small-craft-advisory-rated conditions that kept most recreational boaters off the water. I do not foresee this type of use for my 1992 model.
  • The price differential was significant.
  • I rarely needed all of the horsepower available.

If I had to decide on an engine again, I would look hard at the Suzuki DF90A (lowest price), then the Yamaha F90, followed by the Mercury 90 FourStroke.

Hope this helps.
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AdamT
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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby AdamT » Tue May 24, 2022 3:44 pm

Phil T wrote:DEV--I owned a 1991 Outrage 17 for more than seven years with a F115, and I now own a 1992 model with its original Evinrude 115 two-stroke-power-cycle engine.

I did extensive research in preparation of the re-power and regularly talked to many Outrage 17 owners here and abroad. If you search this forum and the archives, you can read many of my posts concerning the weight sensitivity of this particular model. I do not recommend engine weight over 370-lbs. I ran with all the drains closed and the splashwell was half-full at rest with the F115--not good.

My 1992 is in the middle of a re-power and restoration with an E-TEC 90-HP engine waiting to be installed. I selected the E-TEC 90-HP for the weight advantage.

Unless you are pulling a slalom skier, doing long distance, or high speed runs, a 90-HP engine is only 5-MPH slower at WOT, about 42-MPH versus 46-MPH.

If you are looking for low-end acceleration, consider the recently introduced Yamaha I-4 V MAX SHO 90 or 115 models. They have the same weights as the F90/F115.


I wanted to ask a couple questions since you seem to be a constant contributor regarding first gen 1outrage models.

The 90 E-tec weights 320lb, but also has an external oil tank. Where is your tank mounted?

When you had an older generation F115 (400+ pounds) where did you have your battery or batteries mounted?

Was your F115 Outrage 17 a 1990 with the tank in the rear or the 1991 model with a livewell?

I am repowering a 17 outrage with a yamaha F115 that weights 377 pounds. I previously relocated the battery to the console and added a second battery. I was not concerned about weight until reading your posts.

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Phil T
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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby Phil T » Tue May 24, 2022 7:34 pm

The E-TEC 90 does not have a remote oil tank rather it is under the cowl. The E-TEC 115 does have an external oil tank.

The 1992 Outrage 17 had a 1992 Evinrude 115 that did have an external oil tank when I purchased it. It was installed under the port side rear quarter seat.

My 1991 Outrage 17, which had the livewell feature, had a single battery in the stern. I moved it to the console. This helped reduce the stern weight bias.

At 377, the current F115 is a good option.

I would check the "gap" between the top of the splashwell and the rear cap to ensure it is sealed. Many 1990-1993 boats did not have this gap sealed at the factory. If you "hypothetically" were backing into breaking 2' waves, there is the very real potential to fill the splashwell to the top and have it overfill into the bilge and "hypothetically" partially swamp the boat. Hypothetically. Actually not hypothetically at all. Been there, done that. Not a good time.
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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby AdamT » Wed May 25, 2022 7:05 am

Phil T wrote:The E-TEC 90 does not have a remote oil tank rather it is under the cowl. The E-TEC 115 does have an external oil tank.

The 1992 Outrage 17 had a 1992 Evinrude 115 that did have an external oil tank when I purchased it. It was installed under the port side rear quarter seat.

My 1991 Outrage 17, which had the livewell feature, had a single battery in the stern. I moved it to the console. This helped reduce the stern weight bias.

At 377, the current F115 is a good option.

I would check the "gap" between the top of the splashwell and the rear cap to ensure it is sealed. Many 1990-1993 boats did not have this gap sealed at the factory. If you "hypothetically" were backing into breaking 2' waves, there is the very real potential to fill the splashwell to the top and have it overfill into the bilge and "hypothetically" partially swamp the boat. Hypothetically. Actually not hypothetically at all. Been there, done that. Not a good time.


Good to know. I will seal the transom area. The boat is primarily used to go sandbar hopping in the keys so I had not experienced anything more than 1-2' chop in the bay.

I was concerned about your experience as you seemed to revise your weight from 400 to 370 [right below the F115] to 350 [below F90 range] before settling on a motor in the 320lb range. I was wondering if the revisions had something to do with the specific weights of the newer motors and I specifically steered away of pre-2016 F90/F115 due to the potential for weight problems. Glad to hear this motor shouldn't be a problem.

Any idea on where to start for a prop? Size and pitch since you had a similar set up?

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Phil T
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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby Phil T » Wed May 25, 2022 10:51 am

For a prop, the F115 owners (and myself) run the 13-1/2 x 19-inch Yamaha painted Stainless Steel.

While I moved my engine to 3 holes up, it ventilated in medium speed sharp turns so I went back down to 2 holes up, top bolt in the 3rd hole down from the top.
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Re: 1992 Outrage 17 Re-power Yamaha F90 or F115

Postby kimberlybenson » Wed May 25, 2022 7:05 pm

how much did you pay