Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: prop selection help for 18 outrage
Posted by str8fishon on 12/25/13 - 9:25 PM
#1
Guys I'm looking for some help in prop selection for my 1985 18 outrage. The boat will be running twin 2013 70 hp yamaha four strokes. The engines are on 8" setback manual jack plates. The boat is probably a little heavier then a factory one due to pilot house (much like a pacific pilot house but custom built) along with electronic package (radar, multiple screens, autopilot and multiple batteries under house). I'm not concerned about the added weight since the boat will fish no more then two guys ever and usually one. The boat is only used to fish the ocean primarily from bodega bay ca....but will be towed a few hundred miles north or south depending on the fishing. My main concern is planing quickly. Economy is also important since the boat will be used offshore when conditions are correct. I'm not worried about maxing out the hulls speed capabilities. 35 mph would be more then enough for me and the ocean usually doesnt allow for speeds in excess of that anyways. If anyone has any experience with what worked for them on their 18 outrage I would be interested to hear about it. Or if any prop gurus want to throw in their two cents that would be awesome. Thanks
cj
Posted by Phil T on 12/26/13 - 8:35 AM
#2
CJ-
Entering "F70 prop" into the search engine, selecting "include words" found this thread with an answer to your question:
http://www.whalercentral.com/forum/vi...ost_117172
Keep in mind the mounting height will be different given the static trim of the boat and the jack plates.
We would really like to see some photos of your boat. Sounds like a great setup. Make a personal page :)
Posted by kamie on 12/26/13 - 9:21 AM
#3
Most prop guys need more info, such as what props are on the engines now, what is the RPM at WOT that the engines can reach with the current props and where are the outboards mounted and what it the relation between the cavitation plate and the surface of the water when the boat is on plane and the engines trimmed out? You indicated the engines are Yahama F70's, is one counter rotating which could limit the props you can use? Does the dealer that installed the engines have a suggestion and will he let you test and swap props?
Posted by str8fishon on 12/26/13 - 12:07 PM
#5
Thank you guys for the responses. They have all been helpful. I can add this about the engines. Their max rpm is 5300-6300. They have a gear ratio of 2.33:1 for the lower units. They are both normally rotating since 70 hp engines are not offered as a counter rotating unit. I have no performance numbers or anything because the boat is not yet complete. I'm trying to be prepared for when the day comes to mount engines and go test. I have at least a few months left before this even becomes a reality. Once again thank you for the help.
cj