Prop pitch 38 Tiara open

[William Walter]

read Corey’s article about ovever propping on 480 ce engine .i have 3 bladed 24 by 30 props which register right on the power curve or slightly higher .i have some browning on my turbo and aftercooler. Was planning to have props reconditioned this winter as it’s my first with boat and one prop has a slight nick.what conversation should I be having with my prop guy to get me under the curve

Topic

[Arnie Beems]

Bill,

Thanks for the info. My Tiara is a 2003 38 Open and it has the Cummins 6CTA 8.3 480 M motors. My understanding was 2003 was the first year that Tiara went from the 450 to the 480 motors. And I was told that the 480 M and the 480 CE are the same motors (maybe somebody here can explain the differences, if any).

Jim

[William Walter]

Pitch

Annie wish I had the paper work from the prop shop on boat but but will Ck when I get back.. I think my results were somewhat like yours ..with a clean bottom beginning of season seems to make a big difference.but I think the reality is what you get after being in a while and probably loading the boat up some.i think I’ll probably take some more pitch off but maybe only half an inch and see what happens next year.Bill what year and engines do you have.

[Arnie Beems]

Bill,

Thanks for the info. When I bought my boat, I had my props pulled and adjusted to what I thought was the proper spec of 30″ pitch as originally specified by Tiara. That was of course before I learned all that I have read here. My current fuel burn and load numbers are close to what you where seeing before you adjusted your props (approx. 16gph and high 60% load at 2200 rpm). I had the boat hauled this past winter and had new bottom paint on the hull and running gear – the fuel burn and load with a slick new bottom was probably 10% lower than what I have now. I have divers clean my hull/running gear every two weeks (warm water here in Florida – lots of growth) and I check their work periodically. But even with the hull/gear clean, it still is not as slick as it was after blasting/painting.

I was going to have the prop shop adjust my props to 24 x 28 based on Tony’s comments that it doesn’t hurt to be underpropped. But I am now wondering if I need to take 2″ of pitch out based on your findings.

[William Walter]

Prop pitch

Jim I have 30 x24 also .im on vacation and don’t have paper work from prop shop but remember the start numbers were actually over 30 and I think we ended with 29.25.the 38 with the mechanical are 28 x 24 so we tried to split the difference.i may take a bit more off over winter because the great numbers I saw after first doing it have disappeared .trying to figure if maybe I have something else going on.Bill

[Arnie Beems]

Bill,

Hope you don’t mind me asking – but what pitch did you end up with on your props after final adjustment?

I have the original 24 x 30 on m Tiara 38 Open and am getting ready to have them pulled and adjusted for the same reason you did.

Thank,
Jim

[William Walter]

Filters

Ok started with racers .didnt look so bad but would appreciate any advice as to what would constitute a filter that may cause a problem..

[William Walter]

Rob no vacuum gauges on the filtration.i have that on to do list.never monitored boost before because old gauges were hard to read .i just installed the new gauges as you know so I can see the boost now but have no numbers to compare to.fuel filters have about 75 hours on them but it’s an easy place to start.boat is burning slightly higher than when I brought up from Florida with a full crew ,full full,and a somewhat fouled bottom.i thought maybe boat was much heavier over the course of the season so I left the dingy,engine ,at dock and went out with a light load and got same results.if the spray from the pss boot perhaps was getting sucked in for longer than I thought would that be a factor.

[Rob Schepis]

I know your bottom paint is black — It may have looked clean but did you check that it was not slimey or scummy ?

Based on what I know about your boat and how you use it it’s unlikely the boat has gotten measurably heavier, right?

Is Boost up too?

Are your fuel filters do for a change – the primary(s) and the on-engine filters ?
High vacuum will affect the GPH number as displayed. Do you have vacuum gauges on your filtration?

[Tony Athens]

Hotter fuel will also show up as a higher GPH………….

Tony

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William Walter

[William Walter]

Performance

Rob speed is about the same at 2100 rpm s .it just seems engine s are working harder to achieve that 2100 rpm.higher fuel flow and load.only problem I had this year was boot on stbd pss was loose and I was spraying a bit of water there until I tightened clamps.Bill

[Rob Schepis]

At the same rpm is the SOG still the same as it was or have you lost any speed?

[William Walter]

Loss of performance i

Thought I had my overproping issue resolved but my numbers have gradually gotten worse as season has gone along.typically run at 2100 and am now seeing burns of 14 gals an hour on both engines which is above the recommended.load is also higher on both engines .now about 60 percent whereas it was in low 50s before.i would attribute it to added weight or fouling of the props or bottom but I dove under and props and bottom are clean.now when I open the engines up it gets to 100 percent load whereas it would go to 90 percent in past.ran boat with a light fuel load and got the same results.any recommendations before I start messing with props again.

[Rob Schepis]

You’re saving ~ $10/hour at cruise, so effectively you’re getting paid better than minimum wage to run her….. well done for attending to this.

[Tony Athens]

Very good job.. Your engines should seem way more spunky when getting up on plane too..

 

Tony

[William Walter]

Prop results

After fixing the problem with my stbd engine I was able to go out and test my reconditioned props. I think my prop guy did an excellent job as evidenced by the numbers.

I first ran at 2100 rpm and had a fuel flow of 12.2 port and 12.1 stbd. Load was 52 percent about.  In the past I burned 13.8 and 13.6 at 2100 doing about 22 knots.  I probably averaged 23 today.  I do not have past load numbers for that rpm.

I then ran at 2200 which is where I sea trialed boat at purchase.  Today Port engine was at 13.8 and stbd 13.6 and load was about 53 percent.was averaging about 24.5 knots.  Past numbers were approaching 16 for both and load at 69 percent.  Speed was aboat 23.5 knots.

At full power I got 2680 on both with a load of 88 percent.  Past numbers were 2660 and 100 percent load.  Granted past numbers were a somewhat fouled bottom and present numbers are with a clean bottom.

Bill

[William Walter]

ok sounds like a plan Bill

[Rob Schepis]

William Walter wrote:

Ok got it .props coming off this week and headed to prop shop.hope we get it right.Bill

Here’s what I would do Bill.  Let’s try to eliminate the “hope”.  Take the props to the prop shop and have them scanned “as-is”.  Then let the prop guy tell you what he recommends but do not give him the green light until he hears back from you.  Post here your current scans and what is being recommended and let Tony offer his opinion.

[William Walter]

Ok got it .props coming off this week and headed to prop shop.hope we get it right.Bill

[Tony Athens]

From me————————100% NO..

 

Prop it like the 450/430 C or you are playing with an very expensive fire that will happen….

Tony

[William Walter]

Ok Corry found out my boat had new style head with updated valves plus a cylinder and turbo in 2010. Was this a fix to update engine to the higher hp or a temporary fix due to overpropping.both engines done.have you heard anything about this program.bill

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