I'm sure I can get some good info from the prop gurus here. Here's the form info as best I can.
1. Year, make and model of boat
1989 Wellcraft Fish 18
2. Length, width and base weight of boat, look for boat decal on back of boat
17?10 7?9 beam 1740 lbs (w/o motor)
Around 3200 lbs loaded with fuel, equipment, and standard crew.
2a.What is the maximum recommended HP for your boat
150
3. Number of people and gallons of gas normally on boat
2-3 30 gals (43 max, normally at least 30 to start) 2 batts, 70lb dog
4. What do you use the boat for
Fishing
5. Is it a Deep Vee and if so how many degrees of Deadrise
Yes 14 degrees
6. Year, manufacturer and model of motor
1988 Merc 100
7. HP and gear ratio of motor IMPORTANT
100 HP 2.07-1
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
5000-5500
9.
10. no and no
11. Does it have a hydrafoil, dolefin or trim tabs
Whaletail fins and trim tabs (Bennet)
12. Manufacturer, model, diameter, pitch, number of blades and whether SS or aluminum props. Merc 48-77344-A40L-17P
13. WOT RPM and speed from your current prop 4800 @ 26 mph GPS with extra load on board. 4900 @ 30 MPH with one person
4902 14. Are you at sea level or a higher elevation, give us the elevation in feet ______600____
15 Motor seems to be running fine, new plugs, verified throttle, compression around 100 on all cylinders.
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop.
Props came with used boat. Poor hole shot, slow to plane, low RPM.
17. Does the prop show any damage that you can see
Some wear and small nicks, nothing major.
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
Improved acceleration, better planning, reach proper RPM.
Boat is normally loaded fairly heavy. 2 batteries (One aft and one in the CC), 2 anchors, livewell sometimes full, ice, fishing gear, safety stuff, etc. I come up with right around 3200 under normal situations. It will rarely have much less, will almost never be run with one person on board. The first numbers (4800/26 mph) was with more load than normal, 3 guys, 2 dogs, 10 hp kicker, extra fuel tank. Taking the extras out made the boat much more responsive, but hardly snappy. In reality it's underpowered, but have to work with what we have in that area. Motor seems to run fine, but it is 20 plus years old. No reason to suspect the tach is wrong, but it has not been verified against another tach either.
Trim tabs were added over the winter and do help with planing, but it's still sluggish. Without the tabs, had to move to the bow to get it to plane. Tabs came from a different boat and were free, so they may not be the exact size needed, but they are close. Had the whaletale on it when we got the boat, meant to take it off and try that yesterday, but ran out of time. Need to run 4300 or so to stay on plane.
After reading a lot of these threads and seeing my picture at speed, it looks like the motor needs to move up a notch. It does pick up speed (2 MPH) and about 100 RPM if I trim the motor up. Can't go too far before it start to porpoise. Can control the porpoising with some trim tabs, but then it ventilates in turns in that configuration. So guessing up 1 notch. Was also guessing a 4 blade prop is in order for this boat, at least 15P, maybe as low as 13P.
A specific brand prop suggestion would be nice, I'm not too familiar with what they are designed to do from brand to brand. Sorry for the long post, but tried to get all the info in one posting. Let me know if you need anything else and I greatly appreciate the help.
Eric
1. Year, make and model of boat
1989 Wellcraft Fish 18
2. Length, width and base weight of boat, look for boat decal on back of boat
17?10 7?9 beam 1740 lbs (w/o motor)
Around 3200 lbs loaded with fuel, equipment, and standard crew.
2a.What is the maximum recommended HP for your boat
150
3. Number of people and gallons of gas normally on boat
2-3 30 gals (43 max, normally at least 30 to start) 2 batts, 70lb dog
4. What do you use the boat for
Fishing
5. Is it a Deep Vee and if so how many degrees of Deadrise
Yes 14 degrees
6. Year, manufacturer and model of motor
1988 Merc 100
7. HP and gear ratio of motor IMPORTANT
100 HP 2.07-1
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
5000-5500
9.
10. no and no
11. Does it have a hydrafoil, dolefin or trim tabs
Whaletail fins and trim tabs (Bennet)
12. Manufacturer, model, diameter, pitch, number of blades and whether SS or aluminum props. Merc 48-77344-A40L-17P
13. WOT RPM and speed from your current prop 4800 @ 26 mph GPS with extra load on board. 4900 @ 30 MPH with one person
4902 14. Are you at sea level or a higher elevation, give us the elevation in feet ______600____
15 Motor seems to be running fine, new plugs, verified throttle, compression around 100 on all cylinders.
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop.
Props came with used boat. Poor hole shot, slow to plane, low RPM.
17. Does the prop show any damage that you can see
Some wear and small nicks, nothing major.
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
Improved acceleration, better planning, reach proper RPM.
Boat is normally loaded fairly heavy. 2 batteries (One aft and one in the CC), 2 anchors, livewell sometimes full, ice, fishing gear, safety stuff, etc. I come up with right around 3200 under normal situations. It will rarely have much less, will almost never be run with one person on board. The first numbers (4800/26 mph) was with more load than normal, 3 guys, 2 dogs, 10 hp kicker, extra fuel tank. Taking the extras out made the boat much more responsive, but hardly snappy. In reality it's underpowered, but have to work with what we have in that area. Motor seems to run fine, but it is 20 plus years old. No reason to suspect the tach is wrong, but it has not been verified against another tach either.
Trim tabs were added over the winter and do help with planing, but it's still sluggish. Without the tabs, had to move to the bow to get it to plane. Tabs came from a different boat and were free, so they may not be the exact size needed, but they are close. Had the whaletale on it when we got the boat, meant to take it off and try that yesterday, but ran out of time. Need to run 4300 or so to stay on plane.
After reading a lot of these threads and seeing my picture at speed, it looks like the motor needs to move up a notch. It does pick up speed (2 MPH) and about 100 RPM if I trim the motor up. Can't go too far before it start to porpoise. Can control the porpoising with some trim tabs, but then it ventilates in turns in that configuration. So guessing up 1 notch. Was also guessing a 4 blade prop is in order for this boat, at least 15P, maybe as low as 13P.
A specific brand prop suggestion would be nice, I'm not too familiar with what they are designed to do from brand to brand. Sorry for the long post, but tried to get all the info in one posting. Let me know if you need anything else and I greatly appreciate the help.
Eric
Last edited:
New fuse block, battery switch, extra battery and cables, fish finder/GPS, trim tabs, marine radio, wimpy stereo, extra bilge pump, new livewell pump, wiring and plug for electric kicker, new pedastal seat, refurbed an old 10hp kicker, rod holders, thourough inspection behind every cover knook and cranny I could get to, and probably a couple things I forgot to mention aside from normal maintenance. Would hate to think of the bill if all that was done by a marina. Then again if I was going that route, would have just busted out 40K on a brand new boat. 
