No more halfast

[bacaruda]

It's been a while since I've been here with setup suggestions. I've done most suggested upgrades, and very pleased. Nose cone, hydraulic plate, SeaStar Pro steering. Nice. Baseline was 1988 18'2" Winner Spirit, 1991 175Xri, manual plate, 2 1/4" below. 26" Predator 4 blade. T-Flex Speedo and tach showed 75mph@6200. Calibrated Airguide speedo right there too.
BRAND new Faria speedo and tach now showing 77mph@6100, same on Airguide. Great 1-1 1/2MPH pickup due to cone. Messing with plate didn't help much. Same 26" Predator.
THEN I looked at the GPS I took along for the first time. 69MPH TOPS !
What a bummer, are these instruments that far off? Or, is a land GPS not good? (doubtful)
Hull is 1050lb dry, 400lb mtr, 70lb battery, 70lb fuel, 155lb me, a little over 1700lb in the
water ready to run. Is this 69mph what I should expect? It sure doesn't look or feel that slow.
First time out this year, near the end broke prop too. I think I hit something, not sure,
pics coming.
I've had several prop suggestions, open for more.
Jim.

[FAST RALLY SPORT]

GPS's sure can hurt your fellings, and it's is surprising how much they weigh. I would think that is about right for your speed. Bobby

[bobthebuilder]

Speedos arent acurite.. My speedo say 68 and gps says 70.... most speedos are slower than a gps but ine is oposite.... Go figure that one out huh?

[bacaruda]

I just did a little math with HP/Weight ratio. I know they're not cars but. My HP/* is about 9.7lb/HP. This test boat,
http://www.bwbmag.com/output.cfm?id=...&sectionid=309, being generous, would weigh in about 2600. With a 225
it has a ratio of 11.55lb/HP. That dry hull weighs more than mine does wet, on the water. The motor weighs more, I added for 2
people@160lb, they've got full tank of fuel,? gallons, I had 10. Most of the props ran 70 - 73MPH.
Just trying to make sense, looking for ghost speed!

[bacaruda]

Just tried new to me prop. 27P TrohyPlus. Previous Predators 26P,ran 69@6100~rpm. This ran 69@5500.
Good rpm drop, but dog out of the hole. Problem was the Trophy vented big time breaking plane. At 4 1/2" below pad it is barely acceptable, above that it even feels like shudder/chop. Neither of the Preds. ever did that. The Trophy spins to 3000 out of the hole, then breaks lose. The Preds. spun to 4500, then the older would vent breifly to 6000, then grab, the newer one (broken), wouldn't vent. This is at 1 1/2" higher than the Trophy. Thinking Tempest, would be better, or scared of all these props venting on plane.
Thoughts, suggestions, have small ins. check, low budget.

Thanks,
Jim.

[Mr. Demeanor]

Are you using a blowout ring with the Trophy Plus?

[bacaruda]

No, do tell. I didn't know of such a thing for a through hub exhaust. I'm really considering Tempest, but afraid of just more ventilation.

[eli]

would try a 24 tempest with 3/8 "vent holes might be perfect , had a 20 ' switzer with 200 merc and 24 tempest and ran 75 mph at 6600 rpm,oil injection removed and different tuner , boyesen reeds,with 26 chopper, motor higher on the 6" jackplate minimal water pressure 80 was in reach. but harder to steer.

[Mr. Demeanor]

The hub on a tropy is smaller than a standard lower unit. I want to say its a 4" hub. Mercury makes a plastic ring you fit to the prop that fills in that gap between the hub and the lower unit reducing the anout of exhuast flowing over the hub.
http://www.mertenmarine.com/servlet/...opeller/Detail

[bacaruda]

Eli thanks, part of this excersize is to get the RPM down a little. I've been running 6100-6200 with a 26 Predator. I'd like to get i down to around 5700-5800. AND keep the oil injection.

Mr. Demeaner, I know about the over/through exhaust. My Predators are that configuration. But, they stall about 4500 out of the hole which is almost perfect. But the
Trophy would only pull 3000, with the vents. And is a dog for 15FT OR SO.

Thanks, still open,,,,,

Jim.

[bacaruda]

Still open for suggestions. I don't know how a ring would help breaking plane.
History,
1: Predator 4 Blade 26P, 69@6200, Cobra GPS and Teleflex Tach. Good hole, vents a little breaking plane. 14% slip.
2: Trophy Plus 27P, 68@5400, Livorsi GPS MHP Faria Tach, dog for 10', all vents open, ventilates more planing. 8% slip.
3: Tempest Plus 26P, 66@5600, great hole, all vents open, ventilates more planing. 10% slip.

Had my eye on 26 Trophy on ebay and missed it.

Looking to drop a few RPM from Predator but maybe pick up real 70MPH.
Thanks,
Jim

[2.5_stoker]

if yore looking for more top end you may want to try i big round ear (chopper style prop) and maybe raising the motor a little...you should be able to run a little higher transom height with a over the hub prop wich will get more of the gearcase out of the water equaling less drag and in theory more top end...good luck

shaun

[Charger200]

I ran my Trophy this past weekend (23p) About 3/4'' Below pad to 80mph on the nose(gps) bout 7300 rpm and still pulling in some nasty water(boat traffic) try jackin your motor up with the trophy on there and see what happens.

I acctually found with my boat that the higher then motor was with the trophy and the more trim it actually seemed to pick up some grip and really pull hard rather then lower1''+ where it seemed to slip alot at about 74mph.

The trophys are amazing props and it impresses me everytime i run it.

Shaun hows your summer been? hows the new boat?

[Charger200]

Oh and about the trophy being a pig for the first couple feet. Mine is too if i dont prep the engine(clear it out with a good rev) it will bog a lil then snap. I would try rasing your engine a lil befor changin props. i bet if you come up a good inch n a bit that you will pick up the rpm your lacking.

And i would definitely give a chopper a try. Try looking for one in the 24p range that hasnt been cut, cupped, or worked in any way not even polished and see how it runs. You will need to bring your engine height right up to even or just below to really see the benifits of that style of prop and if you boat is too heavy you might have a lil bit of trouble getting it to perform right away. Mine seems to be VERY picky with engine height and trim

jay