Newbie
 

Hey Guys, newbie boater here. Well, newbie owner. I’ve had the “pleasure” of sitting on the back bench of my father in laws 87 Stingray 22’ for the past 7 years. Learned a lot! But this year wanted to spread my wings and buy my own boat.

I bought a 1998 Wellcraft Scarab 26’ 454. Cut to the chase time. I’m quite pleased with the performance. But recently some boating friends of mine (with way more experience than I) say my boat isn’t performing to its full potential.

At WOT I’m about 4800 RPM and a GPS of
50/ mph. I have a 23 Pitch prop. I’m very pleased with this number but if there is something wrong with the engine/hull/ prop. I’d like to know. I know this is pretty vague and you guys might have more questions. So id be more than happy to answer.

“There is something wrong with your boat” is a statement I would like to have a rebuttal to.

Thanks guys.


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Which 454 do you have? They came in several different models with varying HP. What prop? Is it in good shape? Your current data shows 28% slip which is not good. I would think that boat should be in the low 60's if running right.

Prop Slip Calculator | Mercury Racing

Prop and engine
 

Thanks for the reply.


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https://cimg5.ibsrv.net/gimg/www.off...598a80c2a.jpeg

Does this help?

Do you need anymore info?

Thanks again.

That motor is 385 HP. The Mirage+ prop may or may not be the prop for that boat. I had a 24 Superboat with the same motor. The boat was smaller and lighter but I was turning a 25P Mirage+ to 5000 RPMs. However, the prop caused chine walk and would lose bite in rough water. I switched to a 26P bravo 4 blade with great results. The boat ran in the low 70's.

My suggestions would be to verify that your motor is making the power it should be by getting at least a compression check. Also, try some different props.

Agree with Dave above on checking on health of engine and then playing with props. I'd think that boat should run at least upper 50's/low 60's and you need to be spinning that engine right around 5K RPM at WOT (rev limiter is 5150).

Since you are a new boat owner/operator, as opposed to a passenger, are you trimming the boat out properly at speed?

IMO, you should be running 60ish mph. Your prop slip% is horrible at 28% https://bblades.com/propeller-slip-calculator/

Are you fully trimming out the boat?? Tabs all the way up?? Does the bow lift well when trimming out??

I can't help but that Scarab is a beaut!

Flattered
 

Firstly, thanks for all the responses.

The engine sounds good. There are no misses, knocks or stalls switching between fwd and reverse. But I will most certainly do a compression check.

Trim. When running the boat WOT and adjusting the trim, I hit a point where if I adjust it up or down the boat slows down. So I believe I’m in the sweet spot there? And yes, trim tabs are all up.

As for props.

Where do I begin? Is there a method to choosing what the next prop is?

Again, I appreciate all the feedback and info.

I would try a 22" Bravo 4 blade prop or something very similar.

Something seems wrong, to me. I had a 1998 Velocity, same size, same engine. On a good day and light load it would just hit 72 mph, on GPS. It would rum 69/70 any day of the week. I would expect a Velocity to be faster but not by 20mph! I was running a 25or 26 hydromotive, I can't remember which but I think 25. I would check the engine before investing in a new prop.

Padraig

From an earlier thread someone posted that this is the official factory data with a 502:

1996 Scarab 26
26' 9" LOA
8' Beam
4900 lbs
23º deadrise
Draft: Up 21"
Draft: Down 37"

Factory Specs (502):
195 Mile Range on 502
Time to plane: 6.5 secs
Top Speed: 63 MPH @ 4800 RPM
Cruising Speed: 41 MPH @ 3600 RPM
Tested with Mirage 14 5/8" X 23º Prop

So I would guess the 454 is a few miles slower, probably 58-60 MPH with a prop that works well.

Sorry, I am bad...and old. The engine in my Velocity was a 502 mag, not a 454. Even so 50 mph seems to slow for the OP's boat.

Padraig

FYI, it is very hard to detect a miss on a marine engine with wet exhaust by ear. I'd make sure all 8 cylinders are firing. If you're hitting on all 8 and compression checks out good, might not be a bad idea to have the injectors sent out for testing/cleaning.

Check for hook on the last 4-6' of the hull bottom

Hull Hook?
 

What am I looking for when looking for a hook on my hull?

Thank for the info guys.

Take a long straightedge and set it up lengthwise against the hull in various places at the back. If you see a significant gap between the hull and straightedge anywhere you have a hook. Can be caused by the hull overhanging the trailer bunks too far among other things. Does your boat carry the bow well at speed or does it seem to want to bow hunt?