2002 searay br200 correct prop

[Mastiffrider64]

I have a 2002 Searay BR200, at the moment it has a ss 3 blade (unknown brand) 14.5 x 19p prop on it. My top speed is only 40 mph at WOT and i can over rev the motor to the point the safety kicks in and shuts the boat down. Rpm is reaching 5000 plus this is trimmed out btw. With no trim i can still hit 4800 rpm with a top speed of around 36 mph. This boat suppose to reach top speed of 51 mph, never have seen it myself. This is with 2 ppl both adults and a full tank of gas which is 37 gallons. The hole shot is crap also i can pull a tube getting up to about 32 mph at 3/4 throttle, but cant pull a skier because i cant get them pulled out the water fast enough. The motor is a 5.0 mpi 260 hp, stern drive is a alpha 1 gen 2 geared at 1.62. Motor compression is good, recent tuned up, no skips or nothing. What prop should this boat have on it to get better top speed and better hole shot?

 

[jimmbo]

Better Hole Shot and Higher Top Speed are usually opposing goals.
You have crappy holeshot but you are exceeding the WOT rpm range. Adding pitch to lower the rpms will slow the holeshot even more, and maybe give you 1 mph more. Going to a lower pitch to improve the holeshot will result in an over revving engine/or one planted solidly on the rev limiter, and a lower top speed Most of the problem is a dinky little engine in a 20 ft boat.
How much extra garbage are you hauling around in the boat that could be tossed overboard and never be missed? Ia the hull clean, as in no Algae, or Barnacles? Is the engine in good mechanical shape? Timing set correctly?

There is one prop that can combine better Holeshot and a higher Top Speed, and that prop is called Enertia.

I have an 19 footer with a 5.7 VP with a 2bbl carb, it too puts out 260 HP, but has a lot more bottom end, and can actually accelerate moderately well. My boat:
https://www.youtube.com/watch?v=5WBf2D0103Y

https://www.youtube.com/watch?v=VepbXm5RFDI

That was with an OMC RAKER, it is quicker out of the hole and faster with the Enertia

 

[Scott Danforth]

welcome aboard

my guess you should be in the 15 x 21P range as my 2002 190 with 220hp was spinning a 15x19P solas stainless and almost hitting 50 (very similar hull to yours, without the extended swim platform)

verify your weight. empty hull weight of 3500#, about 4000# full of fuel and gear.

verify your speed with a GPS (not the dash gauge)

you cant have both better top speed and better hole shot on a properly running boat.

you also probably have something amiss with the boat, as you should be hitting about 4800 RPM and about 50mph.

if your numbers are correct above, you are hitting 32% prop slip

when you state good compression, what are the actual numbers? should be about 150psi in all 8 cylinders.

 

[porscheguy]

What is the condition of the prop? Is your speed indicated by the speedometer or gps? Something is amiss because most boats like yours, with your engine and gear ratio are 50mph boats. You’re also at 28% prop slip when most boats like your’s are in single digits.
correction: 28% slip trimmed out, and 32% trimmed in. Either way, this is too high.

 

[Mastiffrider64]

Jimmbo, the hull is clean as i had the boat detailed over the winter. Motor is solid, correct timing and all. The compression in all cyclinders is great because i just had the motor worked on during the winther also and he checked all that when he tuned it up and checked timing. All good.
Besides ice and beer in the dash cooler and towels and such, life vest, and stuff like that normally its me my gf and gas. I do have to 12 inch subs and the boxes they are in under driver and passenger floorboards. But no extra coolers or junk to throw over board.
Scott i have never seen 50 on the dash gauge or gps. 42 was the fastest and that was very early morning before work got choppy. Im running a 14.5 x 19p now and only hitting 40 at wot till the boat dies. Cut switch off, crank it back up and keep on going with less throttle. My avg is 36 mph at 4400 rpms just cruising around. But hole shot is nothing like jimmbos bideo it probably takes me 7 seconds to plain out and normally i have to trimm down to do that in that amount of time. Im going to the lake this weekend and will take videos and such to post and show you what my numbers are. And how the boat is reacting.
Gut the prop is in great condition. No bent spots or nothing, a few scratches but nothing major. No vibration or nothing when i running down the lake. But yeah i think i looked at a calculater last time i went to lake and come up with .2758 percent slip. Which trying to figure hows that when i use the hub kit they recommended with prop. I dont remember which prop it is but its made by quicksilver i do remember that when i bought it.

 

[jimmbo]

I would verify if the tachometer is accurate. 4800 rpm, with 1.6:1 gears, a 19" prop, would yield about 47 mph with 11% slip which would be a reasonable speed for your combo.

If the the tach was set for 5 pulses instead of 4(8 cylinders), the engine would actually be turning about 3850 while the tach would indicate 4800. 3850 would work out to 38.5 mph

You are told the engine is good, as in good compression, timing set to spec. Did the mechanic verify that the timing is advancing as rpms go up? Did the shop dyno it to see if it was performing up to snuff.\
"The compression in all cyclinders is great because i just had the motor worked on during the winther also and he checked all that", really tells nothing. What were the compression numbers?
You might have a blockage somewhere in the exhaust tubes(flapper valve broke loose).
I would be hooking up a vacuum gauge to see what it would reveal

 

[Mastiffrider64]

Yes it was dynoed but i dont know where the print out is that he gave me with all the results on it. But he said it ran like a champ. That everything was solid. Now he did say it was a little slow because of build up on the hull, which is why i had the boat detailed this winter. But it seems to me that its running the same way as when i bought the boat. Top speed of about 40 and i cant run that very long because if i do the warning bell rings and the boat dies. When i had that checked it came back over rev limit reached or something. How would i check to see if the tach is set to 5 pulses and not 4 jimmbo? And once i checked it how would i set it to 4?

 

[porscheguy]

You said only hitting WOT until the boat dies. Then you shut it off and turn it back on. You’ve got something going on here. When you hit the rev limiter, it should only cut ignition until you drop back to 4800 and then it catches and goes again unless it’s different on MPI engines. When it “dies” how much does it fall off? Back to idle? Engine shut off?

Anyone. What is the normal occurrence when an MPI engine hits the rev limiter?

 

[Mastiffrider64]

Engine cuts completely off. My mechanic says its a safety to keep from blowing the motor.

 

[QBhoy]

Hi

this should easily hit the limiter with a 19” and 1.6 ratio. My boat has the same base engine but a 1.47 ratio and can limit easily with a 19” and occasionally a 21” rarely at 5150 rpm.
Im almost positive this is the old famous mpi crap cap that’s responsible.
Get it changed anyway regardless. I’ll bet it’s not helping or probably your issue for sure.
You defo need a 21” I’d say.
50mph is a fair speed for this size of boat, but I’d say it should be achievable with the right prop.
Get the cap and rotor changed out. Google mpi diz cap problems if there is any doubt. It’s thee single biggest issue with these engines.

 

[Mastiffrider64]

Whats the other 2 issues with these engines?

 

[QBhoy]

Whats the other 2 issues with these engines?

There are a couple other than the diz cap. The IAC. The TPS and the SW pressure switch are the main ones.

 

[Mastiffrider64]

Also i was just looking over the parts list on my boat that i found online. The standard 2002 br200 come with an alpha stern drive with the 1.47 gear ratio. Just seen mine has the 1.62 gear ratio.

 

[Mastiffrider64]

And it says im suppose to have a 13.75 in x 21 p vengeance prop. Which from what ive seen or heard thats just a nice fanct shinny prop that has no proformance increase at all. So knowing im suppose to have a 21 pitch helps, but now which prop to go with. A 3 blade, 4 blade or high five? And do i stay at 21p if i go to 4 or 5 blade?

 

[QBhoy]

Personally...3 blade enertia or laser 2 all the way if I was you.
The 1.47 would likely be mated to the 350 mpi option on your boat. Very rare to get a 1.47 and a 5.0 mpi unless it’s a boat like mine...as in much smaller like 18ft

 

[jimmbo]

Too many things aren't adding up here. Your speed attained with your current prop is close to what your boat would do around 3850 rpm. Your tach is reading higher, to which a claim of 27% slippage is occurring. Hmm...

Question, when you shove the throttle lever to fast, I know the boat is slow to accelerate, but do the Engine's RPMs jump up rapidly, or do they take their sweet time? In my video, the rpms hit 3000 rather quickly, due to the venting of the prop then the rpms don't rise as fast, but the boat rapidly speeds up as now the prop is moving a lot of water.

Is there a chance you have a prop with too small of a hub and the exhaust is exiting around the prop and not thru it?
Pic from the side of the gearcase and prop please

 

[Mastiffrider64]

Gotcha. Yeah the owners manual says that the standard 5.0 220 hp comes with a 1.47 but the optional mpi 5.0 came with with 1.62.

 

[jimmbo]

My 5.7 came with a 1.51:1

 

[jimmbo]

Another tidbit of info "the warning bell rings and the boat dies."
You also are saying that when the engine revs to a certain point, it just shuts down? A gradual slow down, or instant off? What else is happening at that exact moment? Alarms? Which one, beeps and/or warning lights? Gauge Readings?

 

[Mastiffrider64]

The warning bell rings when the motor over revs then the boat instantly and completely shuts down. Gauges are reading 40 mph and tach is between 5000 and 5500. Oil pressure is around 40, water temp is in the normal range cant remember the exact number but its good tho. Voltage is good. The only thing high is the rpms. Theres nothing else going on. Just cruising at WOT around 40 mph. Doesnt matter if im going straight or around a slight bend, boat just shuts down without warning. Notmally the warning bell is heard after the boat shuts down but as the boat dies the bell quites ringing. Like i said ill take video of it this weekend while im at the lake and email it to you or try and post on youtube for you all to see.