Boat lists,porposes while on plane.

[alldodge]

IMO a torque tab would not be a benefit with your hydraulic steering, as said before, you have a steering problem along with your porpoise issue

 

[Fed]

So even with the seastar hydraulic steering( not powered hydraulics just normal) i could benefit from a tab? I was told it wouldnt help

The only differences between your hydraulic steering & cable steering is a lower ratio which makes it easier to turn at the expense of more turns lock to lock and also no feed back (NFB) which in this case means that the motor can't turn the steering wheel.
Just because you can let go of the wheel and it stays in position doesn't mean it's not trying to scream towards full lock.

 

[juicegoose]

Okay guys the weather wasn't the best but I have some info for ya. First the stats.

Calm seas
Temp 45 degrees F
Wind <5mph
Full fuel-294#
Two persons - 430#
Boat weight with batteries and misc gear onboard 2000#-2200#
Outboard 500#
Prop 17p Mercury rev4




Trim range for my scientific testing was how many clicks from full in to full out(when tilt engaged). Total clicks was around 32-34 with 14-16 being parallel to the opening of the tunnel/bottom of hull.
Anticav plate was at 1.5" above the top of the tunnel opening when in neutral position and the jackplate was set as low as it would go. The tunnel did angle up as you will see in the pictures but the water flow seemed to be parallel with the top of the tunnel so measurements were taken from that point.

Running info.
-WOT best settings-
-Jackplate all the way up(7.5" from top of tunnel)
-Trimmed out to 15-16 clicks
-No tabs
-RPM around 5300-5400(the little digitach was jumping around some. Also the warning horn started beeping at me when at end of run. Might have actually been hitting rev limiter and the digitach was reading kinda low)
-Speed 48mph
-water pressure stayed upwards of 15-20

Cruise info.
Testing was done at 3500 initial rpms and 4500 initial rpms. Both rpms saw an increase of 2-300 when the motor was trimmed out to 15-17 clicks.

Regardless of jackplate position, all positions only allowed for 15-17 clicks of the trim from fully tucked before the boat would slowly begin to porpoise.
Top speed at 4500 test rpm(4800 after trimming) with motor fully trimmed but jackplate all the way down was 34.5
With jackplate at 3" up and above, speed increased to 40mph.

Steering.
Obviously with the motor fully tucked the steering was horrible. Untucking the motor to 15 clicks or so still saw a little more pressure to port required then starboard but nothing I thought was to much. Inducing some trim tabs allowed for more trim and easier steering if needed. After the test runs I was able to find a seastar dealer that had the purge tube for proper filling of the system. There was some air that came out of the system but very very very little. The steering did feel better though after the maintenance. I wasn't able to retest in the water as the rain had started.

Hull issues.
I did not notice any hooks or rockers in the bottom of the hull when measured with a straight edge.

Boat listing
As you can see in the pictures the boat at rest didn't seem to list to port. If so it was the smallest of amounts.
With two men on the boat I had no need to adjust tabs. The boat rode level. With just me in the boat standing right in front of the wheel(offset on console to port) I did have to add a little trim tab to level out the ride. The port side of the boat also carries the hydraulic system for both the power pole and jackplate. I think with better planning of person placement the listing is gone.

Take a look at the pictures and let me know what ya'll think. The two last ones are from my speed runs. I had a 47mph on the gps and climbing ever so slightly but the motor was all the way up and the trim set to a position that one more click out slowly added a porpoise.

Final Thoughts.
With it all said and done I felt much better about the boat. Yes if I trimmed it out to much it would get hoppy but going into it knowing that not all boats can untuck their motors 100%(rooster tails) and that I was getting half of the trim range out of the motor, and also having the understanding that the steering isn't 100% related to proper trim I was happy with the results.
I think I honestly had a misconception of what I was supposed to be doing trim wise and how the boat should be handling. Learning experience for sure.

Boat listing
As you can see in the pictures the boat at rest didn't seem to list to port. If so it was the smallest of amounts.
With two men on the boat I had no need to adjust tabs. The boat rode level. With just me in the boat standing right in front of the wheel(offset on console to port) I did have to add a little trim tab to level out the ride. The port side of the boat also carries the hydraulic system for both the power pole and jackplate. I think with better planning of person placement the listing is gone.

Take a look at the pictures and let me know what ya'll think. The two last ones are from my speed runs. I had a 47mph on the gps and climbing ever so slightly but the motor was all the way up and the trim set to a position that one more click out slowly added a porpoise.

Angle of tunnel in relation to neutral trim angle on outboard.


Straight edge on bottom of boat for ease of neutral trim placement. Shown here with 14 clicks out from fully tucked.




Outboard at position 0 on jackplate(all the way down) Cav plate 1.5" above top of tunnel.






Outboard all the way up to position 6 on jackplate. Cav plate 7.5" above top of tunnel.





Outboard at position 3 on jackplate. Cav plate 4.5" above top of tunnel.




Boat as it sits in water.





WOT max speed run.

 

[alldodge]

Your boat weight with 1 person = 3209 / 200 hp = 16lb/hp WOT 47mph
My Rinker weights 4500, 1/2 tank fuel 400, 2 people 350, stuff maybe another 100 = 5350 / 300 hp = 17.8lb/hp WOT 60mph
I weight more and have higher top end

That said your prop comes further out of the water, your rpm increases and speed increases. You have the wrong prop, there is to much load on it and by raising the engine, the prop gets to cavitation and rpm increases. The extra rpm slip is giving more speed. Need a 3 blade prop. From the pics your boat is still to far in the water for the speed your doing. I see you getting at least 60mph if not a bit more

As for steering, it should not be hard to steer. A full hydraulic steering can be steered with one finger. Sure the size of the steering wheel has an impact but not that much. Suggest contacting Teleflex/seastar and ask what they think

 

[juicegoose]

Thanks Dodge I have already contacted seastar about the steering. The hydraulic steering isn't power assisted it's just hydraulics instead of cables. In regards to the cavitation I'm not sure I agree that I'm cavitating. I am not loosing water pressure or speed or gaining some wild amount of rpms with the engine jacked up.
I'm sure I could play around with a 19p or possibly a 21p for speed but I mainly carry 5 adults and 2 kids around so getting out of the water and not blowing out in turns is key too.

Any advise which prop you think would work better?

 

[Tail_Gunner]

Could you post the gearing on that engine, If i was your postion the turbo FXP would be the chocie.

 

[juicegoose]

gearing is 1.75:1

I had a local prop guy tell me that a turbo prop was the prop too. This naturally was after I had bought the rev4

 

[Tail_Gunner]

gearing is 1.75:1

I had a local prop guy tell me that a turbo prop was the prop too. This naturally was after I had bought the rev4

At this point the answer see your prop guy there's a lot of performnce on the table andi am sure it will take two or three props to get there.

 

[alldodge]

As theory's go this is how I came up with mine; Installed is a rev 4 - 17 pitch prop and boat does not operate correctly. What was on the boat was a worn out 3 blade 21 pitch prop. A high performance boat which develops max hp does it in the upper rpm band. The engine has very little power in lower rpm so many have ventilation tubes which supply air to the prop so it can develop rpm until it gets on plane and speed.

Ok your boat is not a high powered engine but there is either an issue with being able to supply power through the prop, or you have a weak engine. I'm going to rule out the bad engine side. Your lifting the engine out of the water to increase speed is leaning me to believe the power is not being transferred because the bow is digging into the water. This light boat should run with the engine lower and should pick the now up.

I would like to see what a 19 pitch would do. Prop guys usually don't have an issue letting you try props under the understanding that you buy your next prop from them

 

[Fed]

Is the back of the pocket where it joins the transom clear of the water when you get going and is the pocket vented?

 

[juicegoose]

Pocket isnt vented. Couldnt tell ya if the tunnel is full upon take off. I looked all over the net and my speed is right in the ballpark of what other owners get wide open. Also checked out a couple slip calcs and im getting 5-7% slip which seems good

 

[alldodge]

Pocket isnt vented. Couldnt tell ya if the tunnel is full upon take off. I looked all over the net and my speed is right in the ballpark of what other owners get wide open. Also checked out a couple slip calcs and im getting 5-7% slip which seems good

I'm getting 21.96 percent slip
Pitch 21
Gear ratio 1.75
RPM 5300
Speed 47 MPH
At 5400 RPM slip goes to 23.41
http://bblades.com/propeller-slip-calculator/

Now if I bring it down to 3500 RPM then yes your slip is down.

I'm sure I could play around with a 19p or possibly a 21p for speed but I mainly carry 5 adults and 2 kids around so getting out of the water and not blowing out in turns is key too.

To fix blowing the prop out on turns you need to have the drive further in the water. As the boat turns and your up 3 to 5 above the tunnel becomes 8 to 10 as the boat rolls to one side. With you loading the boat with 7 people you probably need to go down to 17 pitch prop.

 

[juicegoose]

Sorry dodge i think your mistaken. I have a 17p rev 4 on there already. The 21 pitch powertech is my spare prop. But its all wore out. When i first bought the boat i ran wide open with the t top on And about 3/4 fuel and got 50mph at 5300 rpm.

 

[alldodge]

Sorry dodge i think your mistaken. I have a 17p rev 4 on there already. The 21 pitch powertech is my spare prop. But its all wore out. When i first bought the boat i ran wide open with the t top on And about 3/4 fuel and got 50mph at 5300 rpm.

OK my bad

 

[Tail_Gunner]

21p...1.75...5300....50mph get's 17% slip
17P...17.5...5300....47mph get's 4% slip

the spec's below are they correct?

• Model year: : 2007
• Weight: : 497
• Cylinder: : 6
• Bore size: : 3.63
• Displacement ci: : 185.9
• Horsepower: : 200
• Gear ratio: : 1.75:1
• Shaft length mm 1: : 508
• Shaft length mm 2: : 635
• Shaft length in 1: : 20
• Shaft length in 2: : 25
• Engine layout: : v
• Wot rpm floor: : 5000
• Wot rpm ceil: : 5750..............................That's your target rpm
• Stroke: : 2
• Fuel system: : dfi

RPM around 5300-5400(the little digitach was jumping around some.......... Also the warning horn started beeping at me when at end of run. ..........Might have actually been hitting rev limiter and the digitach was reading kinda low)

What need's to be known were your really at 47 mph @ 5400 or 5750


With it all said and done I felt much better about the boat. Yes if I trimmed it out to much it would get hoppy but going into it knowing that not all boats can untuck their motors 100%(rooster tails) and that I was getting half of the trim range out of the motor, and also having the understanding that the steering isn't 100% related to proper trim I was happy with the results.
I think I honestly had a misconception of what I was supposed to be doing trim wise and how the boat should be handling. Learning experience for sure.


Based off that statement id say your still to deep...but looking at the pic below...reallly that's to deep it looks like the prop tip is 3" above the tunnel roof ...Lots of conflict's here i need a cup of coffee..So what does make sense is 5750 true rpm your tach is problably lying to you there worse than polotican's...

21p...1.75...5750....50mph get's 23% slip
17P...17.5...5750....47mph get's 11% slip

And now to your hull im assuming its been painted and a bit rough...not smooth and shiny flat smooth to the touch.

Now it that pic it looks like prop tip is even with the tunnel roof is that correct??

It may seem picky but rpm being exact can play a big role, I/O's engine's are cammed so they fall on there face at about 4500 ...i once propped a boat that ran a 19 alum to 50 at 4900 rpm and noticed a very slight tick at 4900 (revlimiter) to make a long story short a 21p 4blade SS was finally put on and pulled the engine down to 4800 rpm and 56 mph..big differnece. And that engine seem's to have a huge WOT rating.

 

[juicegoose]

Well i know i was doing 48 as that was measured off the gps. The digital tach is normally pretty accurate and measures consistently 300 higher then my analog tach. Sadly i didnt pay attention to the analog tach. I dont really have the funds to be buying all kinds of props. Any suggestions for test props?

 

[redneck joe]

go to where you get your boat serviced and see if you can borrow props.

 

[juicegoose]

Thanks Joe I've asked them before. That is a no go.

 

[redneck joe]

huh. guess i'm spoiled.

 

[juicegoose]

heheheh guess so.