help me understand

[scoutfisher]

old boat-- 1994 blue water eagle. 4.3 with alpha drive. iffin i recall the final prop i ran was a 14 in 19p, 42mph @4400rpms. new boat 1993 sea swirl 190 with omc 5.0 fi. current prop in horrible condition 15 1/2 in 15p. 35ish mph on gps @ 4900rmp.. fully trimmed. if i go to the iboat prop catalog and input my data it recommends this prop. ? am i getting bad run data because the condition of the prop or should i really be looking at a 17 or 19 pitch? i have went thru 10 pages of old posts and dont see anyone recomending 15p props. ?? confused

 

[steelespike]

Re: help me understand

Prop selection is only as accurate as the input.I believe your 4.3 gear ratio was about 1.84:1
there are 2 5.0 ratios 1.65 asnd 1.50. 180hp and 205.
The prop size would depend on the size and weight of the boat.
15 does seem low not leaving much room for prop selection for heavy loads and water sports. The 15 could be on there because the po didn't want to give up his good prop.
or it may have performance issues for any number of reasons.
You may be able to get the prop repaired and get new numbers to tell better what prop is needed.Then you can keep it for a spare.To me a 19 seems reasonable ,not knowing the actual boat size difficult to tell about a prop.