jerryk
Captain
When not online I'm likely on Knot Online
Posts: 597
|
Post by jerryk on Jun 22, 2023 9:41:57 GMT -5
Agree with the 2" drop in pitch when going 3 blade to 4 blade props. That was the case for me when I went from 3 blade 19" to 4 blade 17" on my Carver express cruiser Merc I/O Bravo II drive). Agree with all of the findings that Fritz reports too. But if I replace props at this point I'm going to install Sharrows for the added efficiency and quietness over normal blades. Just waiting for pricing to get more realistic.
|
|
|
Post by Fritz on Jun 22, 2023 9:56:30 GMT -5
|
|
|
Post by finatic on Jun 22, 2023 10:38:41 GMT -5
Stupid question of the day. When you purchase these props you need to purchase a hub kit for them.
|
|
|
Post by Fritz on Jun 22, 2023 11:15:45 GMT -5
Yes, the RBX-203 is for the Rubex HR4. I went the with Rubex to get rid of prop chatter and have been thrilled. Also,never have to worry about having a spun hub again if you buy an extra kit. You can purchase the Titan HR4 which is a standard rubber hubbed prop. But you could still get chatter with that model.
|
|
|
Post by abouttime2fish on Jun 22, 2023 12:43:58 GMT -5
Couple different RBX 203 hubs. This is the first place I’ve found to show applications.
|
|
|
Post by Fritz on Jun 22, 2023 13:00:37 GMT -5
The RBX-203 is the model that would be for be for our applications
150-225 HP (1984 and Newer), 15 tooth spline
The ones I purchased are in my previous post with the Amazon link
|
|
|
Post by fishnfool on Jun 22, 2023 13:51:37 GMT -5
The RBX-203 is the model that would be for be for our applications 150-225 HP (1984 and Newer), 15 tooth spline The ones I purchased are in my previous post with the Amazon link Did you get the Solas Rubex prop or the HR4 Titan?
|
|
|
Post by Fritz on Jun 22, 2023 14:41:49 GMT -5
|
|
|
Post by suprasteve on Aug 12, 2023 18:59:27 GMT -5
Piggybacking on this thread with another 4 blade review. Haven't had my 2660 all that long (8 months now?), but it came with 3-blade 23 pitch props (twin 250 HP Yamahas). The reasons I looked to change props were: ventilation when coming up on plane, especially in rough water. Challenges staying on plane in rougher water (much below 3500 rpm and rear of the boat would drop off plane). With those 3-blades, 3500 rpm was about 32 mph in calm water or ~25 mph in bumpy water. Figured if the same rpm resulted in speeds between 25 and 32, there had to be a lot of slip on the low end of those speeds. 32 mph is definitely too fast for the average offshore day. Swapped to 4-blade Rev 4 props (21 pitch) earlier this week, and ran them today. Initial thought are: popping up on plane was much quicker, and didn't feel like the props would ventilate. The 3-blades even in calm water could be vented if you punched the throttles. Running in calm water to start, it was pretty apparent the motors had plenty of power for the pitch, wouldn't drop pitch much/any more with these motors. The stern lift was apparent too. I ran the boat with the trim tabs down just a hair on the way offshore. Could have probably ran with none and a bit more motor trim. With the 3-blades I was always at least halfway down with my tabs. Part of the intended drop in pitch was to actually slow the boat a bit running around offshore. I could run 27-28 mph at ~3400 rpms and was comfortably on plane. Before, 3400 was iffy for staying on plane, and the boat would be trying to go 30+ mph and speed varied considerably. I also noticed the boat was much quicker to recover when I ran into the backside of a wave. A couple seconds later, I was back up to original rpm/speed with the 4-blades. The 3-blades took much longer to recover from stuffing the bow in a wave. Wind picked up in the afternoon. Not bad conditions, but 12-15 knots and occasional white caps. Cruised in at ~32 mph and 3900 rpms. No tab adjustment at all, ran in with them up. All day I pretty much stayed around 1.7-1.8 MPG in all speeds/conditions. Previously with 3 blades, I could get north of 2 MPG in calm waters, but would often drop to 1.5-1.7 when going through the bumpy stuff offshore.
In short, happy with the way they performed, and for the type of boating I do (longer offshore runs primarily), the 4 blades seem to be an improvement over 3 blades. Slower planing speed, no ventilation coming up on plane, more stern lift/less trim tab usage, and more consistent MPGs overall. Haven't had them out in the nasty stuff yet (generally don't run out in it, but on occasion have to run back in it), so remains to be seen there. I'm likely losing some top end speed (never run that fast anyways), and MPG's weren't quite as impressive as the 3-blades in slick calm water, but I think fuel burn will be about the same since they run a much more consistent 1.7-1.8 MPG instead of anywhere from 1.4 to 2.0 depending on how recently a random wave threw off the boat's rhythm.
|
|
jerryk
Captain
When not online I'm likely on Knot Online
Posts: 597
|
Post by jerryk on Aug 12, 2023 20:44:22 GMT -5
Great review, thanks for the detail and depth of observations since much of what you said will resonate with the Sailfish community. Well done, Captain!
|
|
|
Post by fishnfool on Aug 13, 2023 8:10:12 GMT -5
Rev 4's are awesome props. If you want even more stern lift, the Rev 4s really benefit from sending them to a prop shop to add add some cup. It also improves their bite too.
|
|