Propellers: TROPHY PLUS v. SPITFIRE X7 on 160 DAUNTLESS

Optimizing the performance of Boston Whaler boats
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GoldenDaze
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Propellers: TROPHY PLUS v. SPITFIRE X7 on 160 DAUNTLESS

Postby GoldenDaze » Mon May 30, 2022 2:05 pm

I've been running a Mercury TROPHY PLUS 17-pitch four-bladed propeller on my 160 Dauntless since 2006. In general, I've been quite happy with the results.

See my analysis of the TROPHY PLUS 17-pitch compared to my original VENGEANCE 16-pitch propeller

This weekend I hit something, perhaps a submerged log, and damaged three blades on the TROPHY PLUS. It's still usable, but it's clear that it's time for a new propeller.

One of the new kids on the block since 2006 is the SPITFIRE X7. Like the TROPHY PLUS, it's a four-bladed stainless propeller. Unlike the TROPHY PLUS, it's supposedly designed specifically for 75 to 115-HP four-stroke-power-cycle engines.
My engine is a 2003 Mercury 115 FOURSTROKE with the Yamaha power head

According to the marketing literature, [the SPITFIRE X7] also has various magical and somewhat vague properties that make it ideal for you no matter what, and also makes you handsome and intelligent.

My real question: what's the practical difference between the TROPHY PLUS and the SPITFIRE X7?
2003 160 Dauntless Golden Daze

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Phil T
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Re: Propellers: TROPHY PLUS v. SPITFIRE X7

Postby Phil T » Mon May 30, 2022 2:12 pm

Bob--I am sorry to hear of your propeller strike incident.

I don't know personally what the difference is.

Larry Goltz holds the Spitfire in high regard.

What is the pricing and availability like for the SPITFIRE X7?

Is there a return or restocking fee policy from your vendor?
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Re: Propellers: TROPHY PLUS v. SPITFIRE X7

Postby jimh » Mon May 30, 2022 6:08 pm

GoldenDaze wrote:...what's the practical difference between the TROPHY PLUS and the SPITFIRE X7?
One difference between the SPITFIRE X7 and the TROPHY PLUS may be in the exhaust end of the hub. On the TROPHY PLUS I don't see much flare (if any) in the exhaust hub end. On the SPITFIRE X7 I see a prominent flare.

Phil T wrote:What is the pricing and availability like for the SPITFIRE X7?
Retailers are asking $560 for the SPITFIRE X7.

The Mercury SPITFIRE X7 propeller appears to be a very recent design, as the current Mercury propeller brochure lists it under "New Propellers."

The X7 designator means its is made of the alloy that otherwise is known as UNOBTAINIUM, the secret material used in the ENERTIA series propellers.

The X7 designator also separates the SPITFIRE X7 from the SPITFIRE, which is an aluminum four-bladed propeller. One might infer that the X7 is the same design, just cast in the X7 steel alloy instead of the aluminum alloy. In illustrations in the catalogue the two look similar.

If you buy a SPITFIRE X7, consider getting the FLO-TORQ SSR hub kit. The SSR hub will reduce propeller shift CLUNK with Mercury gear cases.

ASIDE:
Phil T wrote:Larry Goltz holds the Spitfire in high regard.
I had never heard of the Spitfire X7 propeller, but to hear that Larry Goltz has high regard for it, I immediately knew it must be made by Mercury. There is enormous bravado and marketing with all Mercury products, and their propellers do not lack in that regard. And Larry is a lifelong believer, and willing to enthusiastically endorse any Mercury product, no matter if he owns or uses the product himself.

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Re: Propellers: TROPHY PLUS v. SPITFIRE X7

Postby GoldenDaze » Mon May 30, 2022 11:51 pm

If you buy a SPITFIRE X7, consider getting the FLO-TORQ SSR hub kit. The SSR hub will reduce propeller shift CLUNK with Mercury gear cases.
This is a significant problem with the Trophy Plus. It's a heavy prop and causes a huge "thunk" when shifting, as well as a rough idle. If this newer hub kit will help, that would be great.
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TFrere
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Re: Propellers: TROPHY PLUS v. SPITFIRE X7

Postby TFrere » Thu Jun 02, 2022 9:00 am

In addition to my 1985 Whaler 15 Sport, I own a 2011 Mako 18 LTS powered by a 2014 Yamaha F115 with a Mercury TROPHY PLUS 19-pitch four-bladed propeller.

In 2021 I contacted Ken with PROP GODS, and he told me to try the Mercury SPITFIRE X7 propeller. Ken said the maximum boat speed would improve.

I did not then buy the SPITFIRE X7 propeller because the [predicted] small performance increase did not justify the cost of the SPITFIRE X7.

I still plan someday to replace the TROPHY PLUS with the SPITFIRE X7.
1985 15’ Sport with Yamaha F70

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Re: Propellers: TROPHY PLUS v. SPITFIRE X7

Postby jimh » Thu Jun 02, 2022 10:11 am

TFrere wrote:Ken at PROP GODS....said the maximum boat speed would improve [with the SPITFIRE X7 compared to the TROPHY PLUS propeller]
The general benefit of all the Mercury propellers made with X7 (Unobtainium) alloy seems to be that the maximum boat speed will improve slightly compared to other steel propellers.

The X7 stainless steel is apparently is just some formulation of stainless steel that Mercury developed that is a trade secret. Xy was discussed when it was first announced by Mercury, but I do not believe there is a patent on X7. The exact composition of the material generally known as "stainless steel" varies. There are many well-known alloys of stainless steel which are described by three-digit numerical codes, such as 303, 304, 316, and so on.

The X7 stainless is likely just some alloy that Mercury has developed that has good properties for casting propellers. The only observable distinction exhibited by Mercury propellers made with X7 alloy that I know is the propeller blades are generally described as being thinner than the blades on other Mercury stainless steel propellers. The ability to have thinner blades is attributed to use of X7. That thinner blades allow faster boat speeds is an inference that could be made, and I think perhaps that relationship is suggested by Mercury in their promotional literature for the X7 propellers.

Another distinction, but not something that can be observed, is put forth by Mercury that X7 allows for more flex in the blades. The inference I make from that is perhaps this characteristic accounts for the additional claim of X7 created greater durability (at some point described by publicists as "four times greater" durability), perhaps related to deflecting and rebounding in the event of a blade strike rather than bending and taking a set.

TFrere wrote:I still plan someday to replace the TROPHY PLUS with the SPITFIRE X7.
When someday comes, please give us a comprehensive performance report for both the TROPHY PLUS and the SPITFIRE X7.

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GoldenDaze
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Re: Propellers: TROPHY PLUS v. SPITFIRE X7

Postby GoldenDaze » Mon Jul 11, 2022 10:16 pm

The initial boat performance data is in on the Spitfire X7 propeller on my 160 DAUNTLESS. Note that I replaced the Trophy Plus, which was 13.75 x 17, with a Spitfire X7 in 13.5 x15. I delayed and delayed worrying about whether to get a 17-pitch or a 15-pitch pitch. I was okay giving up a little top speed for better acceleration, but I didn't want engine speed to go up too much in my 22 to 25-MPH sweet spot for cruising. Eventually I came across a performance report on the Boston Whaler website for the 160 Super Sport, which used a 15-pitch Spitfire X7 on a 90-HP FOURSTROKE with the same 2.07:1 gear ratio as my 115-HP engine. My 160 Dauntless is significantly heavier than the 160 SUPER SPORT, but my boat has 25-HP additional, and that gave me confidence to try out the 15-pitch propeller

As an aside, it's not easy to find a shop that will "work with you" on propellers. Everybody I spoke with locally said "all prop sales are final." They also said "I don't have any stainless props in stock and don't know when I'll get any." So taking something for a spin just wasn't going to work out.

Qualitatively, the Spitfire X7 propeller is just fine. The boat speed acceleration feels prompt, and engine speeds in my cruising range are not dramatically different. The boat rides and handles much like it did with the Trophy Plus (both of which are WAY better than my Black Max backup prop, which just feels mushy and requires a lot more bow-down trim on the trim tabs to get a decent ride).

The Spitfire X7 holds the water in tight turns even better than the Trophy Plus, and it takes an extremely tight turn to make it ventilate; the engine mounting height is the same and the engine trim is approximately the same. Shifting is now much quieter, though whether that's due to the propeller or to the new Flo-Torq SSR that replaced my old Flo-Torq III, I do not know. Qualitative summary: the Spitfire X7 propeller may be a little faster to accelerate, may hold the water a little better, but it is really not that different than the Trophy Plus.

Quantitatively, the story is similar. Below is a plot of boat speeds at different engine speed (RPM) for all four props that I've tried on the boat over the years. The Spitfire X7 15-pitch has a bit slower boat speed at every RPM setting compared to the Trophy Plus 17-pitch. That's no surprise, but it is perhaps a surprise that it's only a little bit slower. Top boat speed dropped from about 42.5-MPH with the Trophy Plus to about 40.5-MPH with the Spitfire X7.

MPHvsRPM.png
MPHvsRPM.png (27.7 KiB) Viewed 6047 times


Why is it only a little slower? Because at all boat speeds, it has less slip than the Trophy Plus. That's really just another way of saying the effective pitch of the Spitfire X7 is not really a full two-inches-less than the Trophy Plus. To some extent, especially at low speeds, that may be because I had medium vent plugs in the Trophy Plus and solid vent plugs in the Spitfire X7.

SLIPvsMPH.png
SLIPvsMPH.png (30 KiB) Viewed 6047 times


As I mentioned, I was willing to give up a little top speed for acceleration. And to a limited extent, that was successful. The Spitfire X7 is the fastest-accelerating propeller of all that I've had on the boat, but only by a little. Keep in mind that the fidelity here isn't that great; boat speed and engine RPM are taken from a video so they are synchronized, but my GPS appears to provide approximately a one-second (or maybe 0.5 second) refresh. It's also a different GPS than what I used for the older propellers, and the boat now has trim tabs instead of a lower-unit hydrofoil. In other words, this experiment is not particularly well-controlled.

MPHvsSEC.png
MPHvsSEC.png (40.92 KiB) Viewed 6047 times


I'd say that the quantitative analysis pretty much matches the qualitative one -- the Spitfire X7 is maybe a little better on the acceleration, gives a little slower boat speed at all speeds on plane, and holds the water a little better in turns.

For replacing a damaged prop, I'm happy with the results, and I think this prop will work very well for me. But frankly, I'd be pretty disappointed if I had spent $600 looking for some big advantage over the Trophy Plus. Perhaps the biggest improvement came from the $90 Flo-Torq SSR hub kit.

-Bob
2003 160 Dauntless Golden Daze

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Re: Propellers: TROPHY PLUS v. SPITFIRE X7 on 160 DAUNTLESS

Postby jimh » Tue Jul 12, 2022 9:42 am

BOB--thanks for the very comprehensive and excellently presented report on the propeller testing. To have plots of the data is really nice, as you can make comparisons and see trends much more easily in the plots. I think your choice of pitch was right-on.

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Re: Propellers: TROPHY PLUS v. SPITFIRE X7 on 160 DAUNTLESS

Postby Phil T » Tue Jul 12, 2022 11:50 am

Bob -

Did you try Ken at PropGods? He is one of the only, or the only one, who will take back a prop for a small restock fee.

What was the retail price of the X7?

What was the top RPM of the X7? Charts are pretty but I am color blind so its hard for me to tell which is what.

Will be contacting you offline about doing a gathering on your pond.

Regards.
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Re: Propellers: TROPHY PLUS v. SPITFIRE X7 on 160 DAUNTLESS

Postby GoldenDaze » Tue Jul 12, 2022 12:12 pm

Phil, I used Ken's Sports in Wisconsin (boatpropellerwarehouse.com). I don't recall looking at PropGods. Matt at Ken's was very helpful and very up-front about what he had in stock and what he didn't, which was another factor in my changing to 15-pitch from 17-pitch. Nobody seemed to have the 17-pitch in stock, and the delivery time was unknown. The 15-pitch was available. The propeller was $560, and an additional about $90 for the new SSR hub system.

Maximum engine speed in yesterday's testing was 5900-RPM, a little lower than the 6,000 to 6,100-RPM I recorded in the past. Perhaps I could have tweaked the trim a little further and gotten another 100-RPM, but [sea] conditions were not perfect and my ability to run at that speed was limited by other wakes--another limiting factor in my testing.

ASIDE: Having a Smith Mountain Lake Whaler get-together would be a lot of fun!
2003 160 Dauntless Golden Daze

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Re: Propellers: TROPHY PLUS v. SPITFIRE X7 on 160 DAUNTLESS

Postby GoldenDaze » Mon Aug 29, 2022 12:13 pm

Some follow-up info. The Spitfire x7 is working out great, and I got the Trophy Plus back from repair. The prop had a significant ding in the leading edge of two blades and was missing about 1/8" of a third blade, with just some minor scuffing on the tip of the fourth. Considering that I went back to the location on my GPS and determined that I hit a rock shelf, the condition of the prop was amazingly good!

My local shop sent it out to Blackburn Marine Distributing in Pennsylvania for repair 5-6 weeks ago, and I just received it back. It was something of a gamble as I didn't even know what it was going to cost until it came back, but for $280 it is absolutely gorgeous and I'm astonished how perfect it looks.

Before:
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IMG_20220706_083356170_800.jpg (186.12 KiB) Viewed 5715 times


After:
IMG_20220826_151228681_800.jpg
IMG_20220826_151228681_800.jpg (242.94 KiB) Viewed 5715 times


-Bob
2003 160 Dauntless Golden Daze