BradH

Helping a friend set his up… Scarab 302 Sport re-rigged with twin Merc 300xs. 1st set were some old nasty 4b 23s cause we had to go out…during break in we were on the limiters.

Current- 4b 26” stock Merc round ear. With 2 people light load, 5500 rpm max at 68-69 mph. 4000 rpm 45-47 mph, 4200rpm 51 mph, 4500 55 mph. Numbers given over the phone…could be a little off.

Motors go to 6000…we’re 500 shy. Height should be good, the 4s stay in when trimmed out, defiantly need to adjust toe...spinning out.


What’s the experience out there with these boats? Found some older threads, not necessarily with these motors though. We’re thinking a set of 4b 24s or 3b 25s. Any thoughts?

markt111

first thing is to verify all speeds by gps and know your RPMs, props are ecpensive to be guessing on unless you have a few friends to borrow from or get in one of the prop gurus trial programs, also how is the boat to be used? all out speed, cruising, fishing, family,

I have the same hull running 250 hohnson V8s and currently run Mirage plus 21p in the low 60s, I also have a solid T-Top and electronics box which doesn't help performance but this is an all around boat for me and the shade is nice when your out from 6AM till dark.... have tried 4 blades but not Bravos or Rev 4s which should be good on this hull, pretty much try any of the new perf props, I wonder how Enertias or Tempest Plus would run?

I am still working on my setup in between fun times, installed jackplates last year but I have loose motor mounts I need to replace so i can not trim up past 1/4 trim or she gets squirly,

good luck and let us know how it goes

bbladesprops

It looks as though you are running quite well as far as the slip numbers are concerned.

One thing about these motors that is published much is that the HP is very flat post 6000 rpm.

Keep the bigger pitch and Lab them to turn 6200 and you are there.

The only determination is engine height and adjustments to the Lab process to cary the boat well as far as trimming is concerned.

BradH

Numbers are accurate, speed by GPS.

I got 15%, seems reasonable and respectable.

Labbing the 26s would cut them down to about a 25" or so...plus a little working?

If he wanted to stay with a stock prop, as they tend to get torn up around here, what would you recommend? 25s or 24s to hit 6200 with a load? Specific model?

bbladesprops

Labbed 26 Bravo 1's or box stock Bravo 1 24's will get to the 6000 mark and you should be fine.

I get a lower slip. Use 25.3 for the prop pitch.

BradH

Thanks Brett.

I've got another project that I'll come see you at the Miami show about. Brad.

bbladesprops

Nice talking and seeing you at the show!

Let me know when the prop is on its way.

Brett

BradH

Called and left a message at your shop yesterday afternoon...please give me a call when you have a chance...404-406-9518. Thanks Brad.