Go Back  Offshoreonly.com > Technical > Prop Talk
21' Scarab Prop Selection >

21' Scarab Prop Selection

Notices

21' Scarab Prop Selection

Thread Tools
 
Old 03-22-2023, 11:27 AM
  #11  
Registered
Thread Starter
 
Join Date: Oct 2022
Location: WI
Posts: 117
Received 20 Likes on 15 Posts
Default

Originally Posted by Brad Christy
Checkmate,

Not knowing anything about your hull, and just going buy weight, I’m betting you’ll bury the rev limiter with a B28.

Keep your eye out. A B28 just popped up and sold here on OSO. Post in the “Wanted” section you’re looking for one. You might be surprised.

One more thing…. I hope you upgraded the outdrive….

Thanks. Brad.
(937)545-8991
I saw that posting! Too bad I didn't catch it a bit sooner, that guy got a great deal! Stock bravo for now, I'll keep you looped in to what happens with it, will be light on the throttles - again thanks for your replies and insight

Originally Posted by Gimme Fuel
I hope you installed external hydraulic steering! It will be a must in a small hull with that power level. Will be very hard to control any chine walk and properly balance the hull on the keel without it.
I have one added to the cart as we speak, I want to run it stock before I pull the trigger it. I heard this hull gets a bit loose after 65-70mph so I don't plan on pushing it past that often. Will 100% upgrade to external steering in the future, though. Great advice
CheckmateScarab is offline  
The following users liked this post:
Gimme Fuel (03-24-2023)
Old 03-22-2023, 11:29 AM
  #12  
Registered
Thread Starter
 
Join Date: Oct 2022
Location: WI
Posts: 117
Received 20 Likes on 15 Posts
Default

Originally Posted by Brad Christy
SB,

I had a B26 on our PQ while the injectors were giving us fits. After getting them straightened out, we took the boat to the lake to test them out. I couldn't get much above 2/3, maybe 3/4 throttle without bumping the rev limiter. When I reacquired a B28, I can now bury the fun stick and the engine loads out right at 5K RPM.

I'd much rather not be able to use the top end of the throttle range because my knuckles can't get any whiter, rather than because I'm afraid of a rod through the side of the block. Just sayin'...

I didn't catch that the OP had upgraded to a Bravo drive. I thought he was still running the Alpha. All good.

Thanks. Brad.
(937)545-8991
I'd rather have a bit too little prop than too much when starting out, glad to hear the b28 is working in your situation. I'll start with one of those and go from there. May very well end up with a 30 or 32 depending on how it spins
CheckmateScarab is offline  
Old 03-22-2023, 11:49 AM
  #13  
Registered
 
Join Date: Jun 2021
Location: SW Ohio
Posts: 1,531
Received 795 Likes on 444 Posts
Default

Originally Posted by CheckmateScarab
I'd rather have a bit too little prop than too much when starting out, glad to hear the b28 is working in your situation. I'll start with one of those and go from there. May very well end up with a 30 or 32 depending on how it spins
Checkmate,

Yup. Creeping up on it is definitely a wise approach. There are those who might suggest you've got more HP than the hull can handle. I call BS on that. I grew up on a 21' Nordic daycruiser with a 482/6-71/V-drive that my dad affectionately call the "Homesick Angle". It would easily plane off at 2200RPM and could maintain plane at 1900. At 6200 RPM, we were tickling 85MPH and running about as dry as a boat has any right to. Your numbers are going to be different, but I think you're gonna be in that same realm. It's gonna be a hoot. You built all those HP. Now ya gotta load 'em up. I'm betting you're going to spin a B28 like it ain't even in the water. Curious to see how it goes and where you end up.

Thanks. Brad.
(937)545-8991
Brad Christy is offline  
Old 03-23-2023, 01:20 PM
  #14  
Registered
Thread Starter
 
Join Date: Oct 2022
Location: WI
Posts: 117
Received 20 Likes on 15 Posts
Default

Originally Posted by Brad Christy
Checkmate,

Yup. Creeping up on it is definitely a wise approach. There are those who might suggest you've got more HP than the hull can handle. I call BS on that. I grew up on a 21' Nordic daycruiser with a 482/6-71/V-drive that my dad affectionately call the "Homesick Angle". It would easily plane off at 2200RPM and could maintain plane at 1900. At 6200 RPM, we were tickling 85MPH and running about as dry as a boat has any right to. Your numbers are going to be different, but I think you're gonna be in that same realm. It's gonna be a hoot. You built all those HP. Now ya gotta load 'em up. I'm betting you're going to spin a B28 like it ain't even in the water. Curious to see how it goes and where you end up.

Thanks. Brad.
(937)545-8991
That nordic sounds like a screamer! 85 in a 21' seems pretty scary, better have some steady hands! Do you think a 5 blade would be fine in my situation? There is a decent deal on a 5 blade 28" near me, comparatively to new props, at least
CheckmateScarab is offline  
Old 03-23-2023, 01:35 PM
  #15  
SB
Registered
iTrader: (1)
 
Join Date: Nov 2004
Location: On A Dirt Floor
Posts: 13,540
Received 3,115 Likes on 1,402 Posts
Default

Doubtful. Most likely your drive is deep in the water. Most small boats with Alfalfa’s where. This is assuming you didn’t raise drive height when you installed Bravo. Or did you ?
SB is offline  
Old 03-23-2023, 02:33 PM
  #16  
Registered
Thread Starter
 
Join Date: Oct 2022
Location: WI
Posts: 117
Received 20 Likes on 15 Posts
Default

Originally Posted by SB
Doubtful. Most likely your drive is deep in the water. Most small boats with Alfalfa’s where. This is assuming you didn’t raise drive height when you installed Bravo. Or did you ?
Correct, didn't change the height at all, x dimension should be the same. Lower unit has low water pickup, not dual side, but I heard it's the same aside from that change. I should stick to 4 blade?
CheckmateScarab is offline  
Old 03-23-2023, 04:24 PM
  #17  
SB
Registered
iTrader: (1)
 
Join Date: Nov 2004
Location: On A Dirt Floor
Posts: 13,540
Received 3,115 Likes on 1,402 Posts
Default

5 blade is typically for high x dimension when a 4 blade is not grabbing enough water and slipping. Small performance boats don't usually need a lot of blade area. Many run 3 blades also.

Last edited by SB; 03-23-2023 at 06:03 PM.
SB is offline  
Old 03-23-2023, 04:52 PM
  #18  
Registered
 
Join Date: Jun 2021
Location: SW Ohio
Posts: 1,531
Received 795 Likes on 444 Posts
Default

Originally Posted by SB
5 blade is typically for high x dimension where a 4 blade is not grabbing enough water and slipping. Small performance boats don't usually need a lot of blade area. Many run 3 blades also.
Checkmate,

This....

On our Rinker 236 we had before the PQ280, we bought it with a 22P 4B of some unknown make that had been reworked to 21P. The boat rode really wet, and maxed out at about 51MPH. We switched to a 23P 3B of an unknown make (it was an even "try it, keep it if you like it" swap) and the boat came alive. It rode on it ass like it was supposed to and topped out at 60MPH even.

You might try a Mirage Plus 27 or 29P. I'm still betting you'll be over 30P before the engine is happy.

Thanks. Brad.
(937)545-8991
Brad Christy is offline  
Old 03-23-2023, 05:22 PM
  #19  
Registered
Thread Starter
 
Join Date: Oct 2022
Location: WI
Posts: 117
Received 20 Likes on 15 Posts
Default

Spot on, props to you both for chiming in - a few market places have a testing period that I'll take advantage of. Starting with a 28 4 blade and potentially moving to a 30 or 32 as needed. Maybe in the future my curiosity will get the best of me and mess with a 5 blade to see what happens for ****s and giggles
CheckmateScarab is offline  
Old 04-11-2023, 11:59 AM
  #20  
Registered
 
Join Date: Jun 2021
Location: SW Ohio
Posts: 1,531
Received 795 Likes on 444 Posts
Default

Checkmate,

It's a solid hob, but it is a cheap test for a 3B prop.

Mercury Marine Mirage Plus 48-821720 a50 29p | eBay

Thanks. Brad.
(937)545-8991
Brad Christy is offline  


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.