Raised Engines, now starboard prop is slipping - Sailfish 2860, Rev4s

[jski59]

Hi Ken,

I worked with you on props for my old Sailfish 23 and hope you can help here. I have a '08 Sailfish 2860 (same hull as newer 290) with twin 3.3 F250s.

The boat came with the stock 21p SWSII props and frankly, it ran pretty well. However, the engines were mounted a hole lower than the Yamaha perf bulletin and I would get a hint of porpoising now and then, so I just figured they needed to be raised a hole. I also had a leftover set of 21p Rev4s, so I threw them on and liked the additional grip...this is still with the motors "low" in hole #2 (second lowest).

Long story short, last month I finally raised the engines one hole (#3) but now am experiencing slip/ventilation on the starboard motor...t was pretty bad last weekend as seas picked up. I do have B175s transducers mounted on each side of the keel about 1-2ft forward of the engines so maybe that starboard side is causing just a bit more disruption.

Obviously I could go back down a hole, but the boat feels better with the engines raised up a hole. I thought about throwing the larger diameter SWS props back on to see if that helps, but wondering if you had any thoughts on different props or some work to be done on the Rev4s.

Also, is there an obvious way to see if the hub is slipping? I'm running Rubex hubs.

Thanks,
Jason

[ken2]

its not the hub, if it was the hub slipping, you wouldn't be able to get back up on plane.

I'd like you to measure the alignment of the motors.
1. distance between the motors between the leading edges of the gearcases.
2. distance between the motors, center to center on the prop shafts.
See where they are.
then, i'd adjust the tiebar the holds the motors together. (you can lengthen or shorten it with the threaded rod)
I want you to adjust them so center to center between the prop shafts, is 3/4 of an inch SHORTER then the distance between the motors on the leading edge of the gearcase.
Then see how the boat runs.

[DaleH]

...would the rotation of either lower unit, or both, further confuse this issue?

[jski59]

Thanks Ken. I didn’t think about checking toe...boat is two hours away at the marina so it might be a week or so before I follow up.

Ill let you know how it goes,
jason

[ken2]

I've seen some pretty surprising difference in just a small adjustment.
been checking that on quite a few boat the past couple years and it fixed a lot of them.

[jski59]

Once again Ken, you da man! Checked the motors and they were actually toed in a bit...found out Sailfish recommended a 1/4" out so I ballpark set it at 1/2" (although that was in the dark)...and most of the slipping went away. It would still spin now and then, but conditions were pretty rough. I will recheck it with a straight edge next time I'm at the boat but amazed at the difference for a little adjustment.

I didn't track a bunch of numbers but I was cruising at 30mph/3600rpm, 25mph/3200 rpm. With engines lower previously I would run 3 bars of trim, now 2 seems better with the higher mount.

Anyway, since I'll be keeping this boat for awhile I want to get this setup right. Overall its better than the stock 3 blades, but I wouldn't mind a little slower planing speed and lower bow attitude (Sailfish's seem to like to run bow high). Is there anything else you would recommend for a different prop or engine height? My priorities are best efficiency/speed at cruise and slow planing speeds for trolling. I regularly run out 40-50 miles. WOT speed does not matter to me.

Would an eco be worth a shot? OFS4 or BravoLT?

Thanks again,
Jason

[ken2]

Yeah, I'd still go 3/4 of an inch closer on the prop shafts.
Powertech OFS4's would be the most sternlifting of the bunch.