I have posted this question on this site prior and recieved some thoughts from Dhadley - thank you Dhadley. Reading many threads still have me a bit unsure and hoping you can chime in with any thoughts. I hope I filled out the form correctly and was wondering if a newer technology prop could give me a better bottom end without losing top speed. I have pasted the precious post at the bottom of the form for clarity.
Thank you -
Iboats Boat and Motor Info
1. Year, make and model of boat
2002 Nautica Flush deck RIB
2. Length, width and base weight of boat, look for boat decal on back of boat
19' long , 8' 2" beam, total rigged weight with engine, fuel, etc 1,575#?s with no persons on board
2a.What is the maximum recommended HP for your boat
max hp = 150
3. Number of people and gallons of gas normally on boat
3 pob and 25 gal of fuel normal load
4. What do you use the boat for
Mostly used for recreational cruising and some water skiing
5. Is it a Deep Vee and if so how many degrees of Deadrise
It is a deep V (unknown deadrise) with a stepped flat hull at the stern extending about 5' towards the bow
6. Year, manufacturer and model of motor
2002 Yamaha 115 hp 4 stroke
7. HP and gear ratio of outdrive IMPORTANT
If you don?t know the gear ratio, you need to pull the plugs out of the motor and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing then do the same thing on the flywheel and turn the motor until the tape lines up with each other on the prop, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
Drive ratio is 2.15
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
5,000 - 6,000
9. Anti-ventilation Plate height above the bottom of the transom of boat if it is an outboard in inches, use a straight edge or a board under the keel and sticking out to the anti ventilation plate for a reference, and take about 4 pictures for us to see.
Currently at even height to flat center stern."TYPE=PICT;ALT="
10. Is it a bass boat or does it have a pad bottom and is it on a bracket, if so how far does the bracket extend from the stern.
It does have a flat center keel pad much higher then the ?normal? V would have extended
11. Does it have a hydrafoil, dolefin, whale tail or trim tabs and is the motor on a bracket, and if so how far back from the stern is the bracket
None
12. Manufacturer, model, diameter, pitch, number of blades and whether SS or aluminum props.
IMPORTANT
1. Unknown manuf./ no markings - looks like a stick Yamaha aluminum from pictures
2. Aluminum 3 blade 12-3/4 X 21' prop marked on the center hub facing drive / no other marks
3. It is painted white in otherwise good condition
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. Make sure you trim the prop up until it starts ventilating and then just trim in until it quits ventilating. If you do not have a tach you can buy a Tiny Tach for less than $ 50
RPM ___________ Speed (GPS)___________ No. of people ____________ Gal. Gas ________
WOT is 6,200 when trimmed correctly w 3 pob and 40 gals of gas / speed is 52 mph from speedo only but should be pretty close as checked by paralleling other craft with GPS.
14. Are you at sea level or a higher elevation, give us the elevation in feet __________
Sea level
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way by only using the control on the console, checked compression, looked at the plugs and checked spark, is the bottom of the boat clean and barnacle free, and have you checked the Tachometer against a mechanics tach, all of the foregoing could be the reason your prop is not attaining full RPM.
Motor is well tuned and strob tach verified
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop.
I purchased the boat used 3 years ago with this prop and now it is time to select a new one and I am not sure which one to go with.
17. Does the prop show any damage that you can see
None at all.
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations
I believe the prop may be original (a guess) and I want to see if newer technology could help.
It would be nice to have a bit more Ummph at low end for heavy wakeboarders while not losing any top speed.
19. If you are trying to attain a better cruising speed and fuel savings or trying to attain a faster speed I will want you to take your boat and run it with 1 or 2 people and give me the RPM and speed readings starting at 3,000 RPM in 500 RPM increments all the way to WOT.
1. 3000 RPM
2. 3500 RPM
3. 4000 RPM
4. 4500 RPM
5. 5000 RPM6. 5500 RPM
7. 6000 RPM
I do not have ths information at this time.
1. REMEMBER, The prop I recommend will be NO better than the information you give me.
1. smitty477 December 25th, 2009 11:03 AM
Old post follows here....
Rib/115hp/best prop selection
I have a large RIB that I purchased with an existing prop and set up a couple of years ago. I am now in need of selecting another prop and would like to ask which choices may make sense for my application. I have read a bunch of these posts so I likely know just enough information to get myself in trouble here but I will give it a shot anyway. My goal is to get a relatively 'cheap' prop that will allow us to use the boat for recreational cruising and also for some water skiing and toys.
Boat is a 2002 Nautica RIB , flushdeck, 19' long, 8" 2" beam , total weight rigged to use is 1,575#'s, it is a deep V with a stepped flat center hull at the rear. Boat is rated to 150 hp max. , 3,200 #'s , and 16 pass max.
Current prop is aluminum , 3 blade, marked 12 3/4 - 21" on the inner center hub, no manufacturer marks, white, good condition.
Motor - 2002 Yamaha F115 4 stroke, 2.15 lower , good condition, tach checked w/ strobe. WOT range is 5,000 - 6,000.
Mounting - currently mounted with antivent plate even with flat center keel. Was mounted 3/4" higher (2nd hole) then keel when originally purchased but prop would blow out at all trim settings other then almost all the way 'in'. There are no doel fins, trim tabs, or other 'stuff' back there.
Current performance - with 3 pob , 3/4 fuel (more then normal) - we can always reach WOT of 6,000. With trim all the way 'in' we plow pretty badly and get 5,800 and 45 mph (gage only, not verified) , at about 1/2 trim 'out' we get 6,000 rpm + and a gage reading of 52 mph, at full trim out we still get blowout but at a second or 2 trim in from full out we get 6,200 rev limited. It will plane and cruise with 6 -8 adults on board with no real issues. We have no problems pulling a skiier at about 3,500 rpms on slalom. What are my options and what else can I do to help determine this?
Thanks
Dhadley December 25th, 2009 11:44 AM
Re: Rib/115hp/best prop selection
If it works that well with a small diameter 21 I'd consider something like a 13 1/4 x 23 4 blade. If you're interested and have trouble locationg one shoot me an IM or email.
smitty477 December 26th, 2009 10:19 AM
Re: Rib/115hp/best prop selection
Thank you Dhadley,
Although I have not tried any other props on this boat yet I would be a bit concerned that the extra diameter, blade, and pitch would adversely affect the ability to pull up a skiier. Of course with my knowledge so far I could be absolutely wrong about all of this and that is the reason for the post. My 'kids' tell us that they do have some difficulty in pulling up heavy wakeboarders right at the beginning untill they transition up on plane.
Is there such a thing as a replacement prop from what we have that will give us a bit more low end pull but still maintain or increase the top end performance? Is there anoither way I can help identify the existing prop for the folks on this board.
Thanks again
Thank you -
Iboats Boat and Motor Info
1. Year, make and model of boat
2002 Nautica Flush deck RIB
2. Length, width and base weight of boat, look for boat decal on back of boat
19' long , 8' 2" beam, total rigged weight with engine, fuel, etc 1,575#?s with no persons on board
2a.What is the maximum recommended HP for your boat
max hp = 150
3. Number of people and gallons of gas normally on boat
3 pob and 25 gal of fuel normal load
4. What do you use the boat for
Mostly used for recreational cruising and some water skiing
5. Is it a Deep Vee and if so how many degrees of Deadrise
It is a deep V (unknown deadrise) with a stepped flat hull at the stern extending about 5' towards the bow
6. Year, manufacturer and model of motor
2002 Yamaha 115 hp 4 stroke
7. HP and gear ratio of outdrive IMPORTANT
If you don?t know the gear ratio, you need to pull the plugs out of the motor and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing then do the same thing on the flywheel and turn the motor until the tape lines up with each other on the prop, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
Drive ratio is 2.15
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
5,000 - 6,000
9. Anti-ventilation Plate height above the bottom of the transom of boat if it is an outboard in inches, use a straight edge or a board under the keel and sticking out to the anti ventilation plate for a reference, and take about 4 pictures for us to see.
Currently at even height to flat center stern."TYPE=PICT;ALT="
10. Is it a bass boat or does it have a pad bottom and is it on a bracket, if so how far does the bracket extend from the stern.
It does have a flat center keel pad much higher then the ?normal? V would have extended
11. Does it have a hydrafoil, dolefin, whale tail or trim tabs and is the motor on a bracket, and if so how far back from the stern is the bracket
None
12. Manufacturer, model, diameter, pitch, number of blades and whether SS or aluminum props.
IMPORTANT
1. Unknown manuf./ no markings - looks like a stick Yamaha aluminum from pictures
2. Aluminum 3 blade 12-3/4 X 21' prop marked on the center hub facing drive / no other marks
3. It is painted white in otherwise good condition
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. Make sure you trim the prop up until it starts ventilating and then just trim in until it quits ventilating. If you do not have a tach you can buy a Tiny Tach for less than $ 50
RPM ___________ Speed (GPS)___________ No. of people ____________ Gal. Gas ________
WOT is 6,200 when trimmed correctly w 3 pob and 40 gals of gas / speed is 52 mph from speedo only but should be pretty close as checked by paralleling other craft with GPS.
14. Are you at sea level or a higher elevation, give us the elevation in feet __________
Sea level
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way by only using the control on the console, checked compression, looked at the plugs and checked spark, is the bottom of the boat clean and barnacle free, and have you checked the Tachometer against a mechanics tach, all of the foregoing could be the reason your prop is not attaining full RPM.
Motor is well tuned and strob tach verified
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop.
I purchased the boat used 3 years ago with this prop and now it is time to select a new one and I am not sure which one to go with.
17. Does the prop show any damage that you can see
None at all.
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations
I believe the prop may be original (a guess) and I want to see if newer technology could help.
It would be nice to have a bit more Ummph at low end for heavy wakeboarders while not losing any top speed.
19. If you are trying to attain a better cruising speed and fuel savings or trying to attain a faster speed I will want you to take your boat and run it with 1 or 2 people and give me the RPM and speed readings starting at 3,000 RPM in 500 RPM increments all the way to WOT.
1. 3000 RPM
2. 3500 RPM
3. 4000 RPM
4. 4500 RPM
5. 5000 RPM6. 5500 RPM
7. 6000 RPM
I do not have ths information at this time.
1. REMEMBER, The prop I recommend will be NO better than the information you give me.
1. smitty477 December 25th, 2009 11:03 AM
Old post follows here....
Rib/115hp/best prop selection
I have a large RIB that I purchased with an existing prop and set up a couple of years ago. I am now in need of selecting another prop and would like to ask which choices may make sense for my application. I have read a bunch of these posts so I likely know just enough information to get myself in trouble here but I will give it a shot anyway. My goal is to get a relatively 'cheap' prop that will allow us to use the boat for recreational cruising and also for some water skiing and toys.
Boat is a 2002 Nautica RIB , flushdeck, 19' long, 8" 2" beam , total weight rigged to use is 1,575#'s, it is a deep V with a stepped flat center hull at the rear. Boat is rated to 150 hp max. , 3,200 #'s , and 16 pass max.
Current prop is aluminum , 3 blade, marked 12 3/4 - 21" on the inner center hub, no manufacturer marks, white, good condition.
Motor - 2002 Yamaha F115 4 stroke, 2.15 lower , good condition, tach checked w/ strobe. WOT range is 5,000 - 6,000.
Mounting - currently mounted with antivent plate even with flat center keel. Was mounted 3/4" higher (2nd hole) then keel when originally purchased but prop would blow out at all trim settings other then almost all the way 'in'. There are no doel fins, trim tabs, or other 'stuff' back there.
Current performance - with 3 pob , 3/4 fuel (more then normal) - we can always reach WOT of 6,000. With trim all the way 'in' we plow pretty badly and get 5,800 and 45 mph (gage only, not verified) , at about 1/2 trim 'out' we get 6,000 rpm + and a gage reading of 52 mph, at full trim out we still get blowout but at a second or 2 trim in from full out we get 6,200 rev limited. It will plane and cruise with 6 -8 adults on board with no real issues. We have no problems pulling a skiier at about 3,500 rpms on slalom. What are my options and what else can I do to help determine this?
Thanks
Dhadley December 25th, 2009 11:44 AM
Re: Rib/115hp/best prop selection
If it works that well with a small diameter 21 I'd consider something like a 13 1/4 x 23 4 blade. If you're interested and have trouble locationg one shoot me an IM or email.
smitty477 December 26th, 2009 10:19 AM
Re: Rib/115hp/best prop selection
Thank you Dhadley,
Although I have not tried any other props on this boat yet I would be a bit concerned that the extra diameter, blade, and pitch would adversely affect the ability to pull up a skiier. Of course with my knowledge so far I could be absolutely wrong about all of this and that is the reason for the post. My 'kids' tell us that they do have some difficulty in pulling up heavy wakeboarders right at the beginning untill they transition up on plane.
Is there such a thing as a replacement prop from what we have that will give us a bit more low end pull but still maintain or increase the top end performance? Is there anoither way I can help identify the existing prop for the folks on this board.
Thanks again