New member with some questions

[Chiefsurfer]

Hey there guys. I bought a 1987 Wellcraft V20 last year. Boat came with a 1999 C150 yamaha(commercial), with what I believe is a 19" stainless prop. Great boat the few times i was able to get out on it, while trying to get all the work done I want.

When i went out last summer, I was getting ROUGHLY 40 mph, WOT, at only 5000 rpm. It's plenty of speed for me, as I can rarely actually take the conditions at that speed. I just know that the optimal fuel burn and performance is at reccomended WOT, which for this motor is 5000-5500. That was half tank of gas, lightly loaded. I am thinking I can maybe go to a 16" 4-blade, pick up the 300 rpm or so, and get a little faster plane.

Is 40 mph, at 5000 what you guys have found with a carb'd 150. People with yamaha's would be great, but realistically, if you guys are getting between 38 and 43, with your 150's at 5,000 rpm I think im in the range.

Oh, and glad to be here!!

[reelapeelin]

Welcome Chief...my experience has been a 15 to 15 1/2" dia x 17 P prop will deliver best performance and fuel efficiency on a 150 HP...and try to make it a stainless prop if the boat budget allows

post up some pics of your V when you get a chance...we likey V20 porn...

[Destroyer]

Originally Posted by reelapeelin

Welcome Chief...my experience has been a 15 to 15 1/2" dia x 17 P prop will deliver best performance and fuel efficiency on a 150 HP...and try to make it a stainless prop if the boat budget allows

post up some pics of your V when you get a chance...we likey V20 porn...

X2 I second what Reel said... Also, not sure if a 4 blade will get you higher revs.. I think the opposite is true... It gets you a faster hole shot for sure.. but I think you lose at top end... I could be wrong.. I might have my figures backwards. But in all cases a 3 blade SS 17p should be just about gravy for that engine. Oh...and welcome to the site

[reelapeelin]

Originally Posted by Destroyer

X2 I second what Reel said... Also, not sure if a 4 blade will get you higher revs.. I think the opposite is true... It gets you a faster hole shot for sure.. but I think you lose at top end... I could be wrong.. I might have my figures backwards. But in all cases a 3 blade SS 17p should be just about gravy for that engine. Oh...and welcome to the site

Destroyer, yer right on the money re the 4 blade prop...better hole shot, shaves a little off the top...also has stern-lifting tendency which would not be a bad thing for a V20...

[RWilson2526]

i hav a 17P prop on mine and th that's EXACTLY the performance I get with my 1986 150 Yamaha.....40 mph at 5000 rpm... I've thought about monkeyin with the prop to get closer to 5500 rpm at WOT and see what I get but not really on my priority list....also figured being an 86 that it just might be a little too tired to spin up to 5500.

[Chiefsurfer]

Thanks guys, I will have a closer look today. Sadly, there is no size stamped into the prop, where a size should be, there is just a number and letter stamped into the side of the prop housing.

I will post a few pics once I get her all done. Just painted the hull sides with medium blue brightsides. After about 25 hours of sanding the old tired gelcoat. I am going to do touch-up bottom paint to re-establish my water-line, and once it looks "perty" i will post pics. Also will be doing a good wash inside and out, will post pics then too.

Well if you guys say a 17 3-blade, i was thinking of going with a 15 4-blade. I know when you go from a 3 to 4, you want to drop your pitch 1-2" to keep your RPM pretty close to the same spot. I will have to go see what prop i got on her.

[Destroyer]

Originally Posted by Chiefsurfer

Thanks guys, I will have a closer look today. Sadly, there is no size stamped into the prop, where a size should be, there is just a number and letter stamped into the side of the prop housing.

I will post a few pics once I get her all done. Just painted the hull sides with medium blue brightsides. After about 25 hours of sanding the old tired gelcoat. I am going to do touch-up bottom paint to re-establish my water-line, and once it looks "perty" i will post pics. Also will be doing a good wash inside and out, will post pics then too.

Well if you guys say a 17 3-blade, i was thinking of going with a 15 4-blade. I know when you go from a 3 to 4, you want to drop your pitch 1-2" to keep your RPM pretty close to the same spot. I will have to go see what prop i got on her.

Sounds like a Michigan Wheel. Look at the front of the prop hub.. next to the thrust washer. Should be a couple of letters and numbers stamped into the metal right next to the splines.

You're right on the money about droppng your pitch on the 4 blade. That extra blade gives you a lot more thrust at your bottom end.. but it also takes more power for your engine to spin it, so you lose a little at your top end. In fact, the fastest prop for top end is a 2 blade, but you run into vibration problems with them. For our kind of recreational boating 3 blades is about right for most people.

[Chiefsurfer]

Yeah, I don't care about losing the top-end, so long as it's not straining the motor any more. I think the added sternlift will be a good thing(i am already having a LITTLE trouble trimming down), and I am much more interested in quick on plane, over top speed.

I can do about 30 mph, at 3900, which is a PERFECT cruise for me in most conditions.

[RWilson2526]

Welcome to the site by the way Chiefsurfer.....if you want a center console to aspire to following is a picture of our resident primo center console. Hopefully not offending any other center console owners but having seen it in person it is the baddest. (if that's a word)

[Hedge]

Originally Posted by Chiefsurfer

I will post a few pics once I get her all done.

We like pictures to follow a project through. That way it is available for all to learn from now and later on as well.