2011 SUNDANCE B20CCR with 90HP YAMAHA 4 stroke

[THEFERMANATOR]

I've got a 2011 SUNDANCE B20CCR that I picked up with a matching 2011(production date of 04/10) YAMAHA 90HP 4 stroke, and an ATLAS micro jacker, and it has a HORRIBLE porpoising problem. I purchased the boat in need of work, so I wasn't able to test run it before I bought it. It came with a YAMAHA 15 pitch aluminum semi cleaver style prop with a little bit of burning on the blade tips from being run with the jack plate up, but not that bad. In my opinion the boat is unsafe to run with the YAMAHA prop on it as it bounces VIOLENTLY with the engine tucked in fully. It topped out at 6100 RPM's and 34 MPH with it for the short run that I was bold enough to try it. I had a 4 blade SOLAS AMITA 17 pitch left over from my previous HONDA, so I picked up a thrust washer, modified it to fit the HONDA prop, and put the SOLAS on. With the SOLAS on, it runs OK on flat water, and I can trim it some, but the slightest chop or wake, and it goes to bouncing out of this world. It tops out at 5900 RPM's and 38 MPH with the 4 blade SOLAS prop. SUNDANCE reccomends either the 15 pitch 3 blade aluminum or a 3 blade 16 pitch performance series stainless(the test results on the stainless prop are 5900 RPM's and 39.5 MPH).

I know the jack plate isn't helping the porpoising problem, nor is having dual batteries in the stern of the boat(I don't want to lose storage space in the bow to move them as the storage space was one of the selling points with the wife). In the past I have added the STINGRAY HYDROFOIL to my skiffs and jon boats to stop porpoising, but I would rather "fix" this one correctly than install a band aid as this boat is just to nice to use a band aid on it. What props should I be looking at to correct this, or is a hydrofoil going to be my best bet? The SOLAS 4 blade is reccomended for extra stern lift, but it still porpoises with it. I don't want to spend the money for a stainless prop, and then still end up buying a fin to put on it to stop it is all.

Also, I'm not real familiar with what RPM's this 90HP YAMAHA wants to turn WOT. I know YAMAHA says 5000-6000 RPM's, but after 5700 it just sounds like it's running out of air to me. I know my 75HP HONDA(2005 carbed model) had a 5000-6000 RPM band on it, but it liked turning 5600-5700 RPM's WOT I found. A 15 pitch SOLAS turned 5900 and topped out at 28, went to the 17 and it picked up to 36, and spun up to 5700 RPM's.

Any help with this is appreciated.

[ken2]

I would normally suggest a 17 pitch SCD4. But I have an 18 pitch sitting here beside my desk hubbed for a yamaha.

Its a stainless 4 blade with a semi clever design. normally gives good sternlift and hooks up well.

for $30 plus shipping you can give it a run and see what happens.

Those hydrofoil things are ok if you have the motor up high enough, cause they are above the surface of the water at speed.

I'd give this SCD4 a run and see what you think.

As for RPM, I like to turn the 90 4 stroke 5700-6100 if you turn 5600-5700 its fine, but when you put a little more load on it, you'll really feel it.

[blaster]

Do you have room for trim tabs? Even smart tabs would go a long way to lift the stern and reduce porpoising. My whaler has a porpoising issue. When I got it, it had a stingray foil installed. It was okay, without it there wasn't much trim range. I added the 30# smart tabs and took off the stingray, amazing results. Lower planing speed, slightly higher top end and no porpoising in my safe trim range. Well maybe trimmed out in 2' waves I can make it porpoise, but trim in stops it immediately.

[THEFERMANATOR]

This hull really isn't good for tabs. Most of the trailing edge is curved, so it would take a good bit of glassing to get a flat surface to atatch a set of tabs to. I know somebody else who had an older version of this hull(Same basic hull, but didn't have as fancy a liner in it), and with a 90 MERCURY 2 stroke he had no problems with how his ran even with a basic 3 blade stainless prop. I know the added weight of a 4 stroke plus a jackplate setting it back even furthur is what is giving me the porpoising problem. I had been looking at the SCD4, and had a call in to POWERTECH about a reccomendation from them. I plan on picking up a 15 pitch MICHIGAN WHEEL VORTEX 4 blade XHS to use on it for when I go to the rocky areas, but want a stainless to use for the rest of the time. I used to do most all of my fishing out of the nature coast(VERY rocky area if you're not familiar with it), so I've always stuck with aluminum in the past, stepping up to stainless is a big step up for me, then again this boat was a rather big step up from my usual fishing flats boats.

And my last skiff was a 19 DLX with a 05 75HP HONDA. Everybody kept telling me to prop it at redline. I propped it with a 15 pitch AMITA 4 which turned 5900 at 28 MPH, and was told I was good to go, problem for me was it ran 34 at 5600 with a 17 pitch AMITA 3, tried an AMITA 4 17 pitch, and it ran 36-37 at 5600-5700 RPM's. That was one engine that had a NARROW power band, and did not like RPM's. On the flip side, it only turned 5300 at 34 MPH with a MW VORTEX 4 blade 15 pitch.

[ken2]

Well, let me know on the SCD4

Your Honda results are not really common. Gaining 28% top speed on two inches of pitch is nuts.
That Amita 15 pitch was likely not cupped right or something was off with it.
your slip ratio was 24% with the 15 pitch. and 9% slip with the 17.

Props do vary quite a bit out of the box.

[THEFERMANATOR]

I'll try and give you a call this week to see about trying out the SCD4 you have. Talked with powertech(different guy than I talked to the 1st time), and his recommendation was a bit puzzling. He suggested an SCD3 15 pitch. I told him I wanted to lower my WOT RPM's down, and the boat test report of my boat with a 16 pitch YAMAHA ran 5900 RPM's. Thinking I need to go with an SCD4 16 pitch. I want good hole shot(it's a flats fishing boat, it needs to be able to get on plane shallow), the ability to be able to run with the jack plate up some if needed, good cruise, and stop the porpoising. He was worried about me losing top end going to a 4 blade, but I told him that was unimportant to me, and I was already running an aluminum 4 blade with near the same performance as the 3 blade stainless as the factory boat test.

[ken2]

It will depend on speed. (how much if any you loose) I think you might actually gain a little.

If so, this pretty 18 by my desk should run well.

But even if its a little low on RPM, you'll figure out if that style prop gets along with the boat and jackplate.

[THEFERMANATOR]

Tried another prop this weekend. I tried out a MICHIGAN WHEEL 941415 15 pitch aluminum 4 blade VORTEX XHS prop. I want to have an aluminum prop for when I go to rocky areas, so I picked one of these up to try out. I will probably swap it out for a 17, but I'm a little apprehensive to. I was loaded a good bit heavier this time, I topped the tank off(23 gallons added to top off the 33 gallon tank), had the wife and both boys with me, and all of the gear to go along with a 3 year old and 9 month old. The boat seemed to dip down more in the stern getting on plane, and rode slightly bow higher than the SOLAS with al ight load, but I was able to trim the engine up some without it porpoising. This prop topped out at 5900 ROM's and just a hair over 35 MPH. It stayed on plane at 4200 running 22 MPH, but like I said somehow it feels to be running stern low bow high, yet it didn't porpoise like the SOLAS did. It also felt a bit slower to get on plane. I kicked myself in the but because I forgot to bring the SOLAS with me to do a back to back comparison. This load is within 200 pounds of a heavy load for me, but will be considered a semi average load for most outings. It looks like a 16 pitch would be just about ideal in this type of prop. I new the SOLAS would turn more RPM's than the MICHIGAN WHEEL from running one on my last Carolina Skiff 19 DLX with a 75HP HONDA.

Heres a pic of the 2 props side by side. The MW has alot larger blade, a good bit less rake, and a big cup on the trailing edge of the blade.

[ken2]

Well, it sounds like it did pretty well with that aluminum prop.
Weird that it runs more bow high, but does not porpoise as much as the others, But I've seen crazier things I suppose.

[THEFERMANATOR]

Had a chance to slip out and run the boat real quick today(crappy weather, but the wifes going out tommorrow, so I'm stuck with the kids). I ran the boat with the SCD4(it was a stamped as a 19 pitch, not an 18), and it is WAY to much prop. It was sluggish to say the least getting on plane, but it kept the bow down planing, and didn't squat real bad. I had a full tank of fuel, myself, my wife, both kids, and one dog. The wife, kids, and dog stayed in the bow for the most part, but even with the extra weight up there, it still porpoised. With this prop when it porpoised, it was violent like with the YAMAHA aluminum prop. It only topped out at 4900 RPM's(got up to 5000 for a second, but had to trim it in all the way and slow down to get it back under control) and 35 MPH. Things felt good until it broke about 32-33 MPH, then it was like the bow just fell down and started bouncing. Swapped back over to the SOLAS, and it topped out around 5750-5800 at 36MPH, and I could trim it out some, but not much. It squats noticeably more planing with the SOLAS, and ran slightly nose higher on plane, and didn't really stay up on plane like the SCD4 did(couldn't really keep it on plane at slow speeds with the SCD4 because it would lug when I tried to check it, and the RPM's would just drop). Swapped back to the MICHIGAN WHEEL, and it drops down in the stern planing, bow comes way up, but it's still the smoothest running of all the props so far. This thing has me baffled, it's beginning to look like it will take a fin to hold the bow down.

[ken2]

Shoot, I could have swore that was an 18, obviously not.

when you raise and lower the motor on the jackplate does it help with the porpoising?

[THEFERMANATOR]

Didn't seem to do anything but increase the amount of water kicking off the prop. It did throw up alot more water than any of the other props do. I really liked how it ran until I opened it up. Once it got close to as fast as it would go, it's like the bow just dropped down and started bouncing on springs. Trimmed all the way in and it slowed it, but didn't stop it whereas the other props it would stop if I trimmed in all the way. This prop did stop almost all the squatting getting on plane, the bow didn't come up much, and it did seem to ride nice and high while cruising. Other than top end it did well. A 16 or 17 pitch would probably have helped getting on plane, but just don't know what to do about the porpoising on the top end.

[ken2]

Yeah, you may end up wanting an RXB4, which gives a lot of overall lift. Maybe that would do well during planing, but still do ok at wide open.

Weird that the bow dropped and it started porpoising so bad with the SCD4.

[THEFERMANATOR]

It had the bow down nice with it running right up until it went to bouncing. But I could tell from the ride it wasn't really pushing the bow down hard. It only has a V to it in bow portion coming up, the bottom of the hull is pretty much flat as can be, and it was not riding very smooth on a small chop with the SCD4.

[ken2]

well, my bet would be the RXB4.