Prop size question: 1988 Wellcraft 200 Classic, 200hp/V8 merc

[hackr]

am looking for the OEM prop size and/or recommendations for my Wellcraft...it has the 5.0L 200HP/V8 merc engine...picked this up pre-owned and put a 14.25R21 stainless 3 blade Rapture prop on it from my 17' Wellcraft - which i sold...since i swapped props (to keep the stainless), i don't know what was originally on the 200 Classic...the 200 Classic is open bow, 19' 6" in length, 8' beam and weighs 2600 pounds...

i use the boat mostly for cruising...not sure if my speedo is off, but i only could get it to 42mph...the RPMs were 3800...i will try to use a GPS this weekend to check the speed...

any info/advice is appreciated...

R-

 

[Bondo]

Re: Prop size question: 1988 Wellcraft 200 Classic, 200hp/V8 merc

am looking for the OEM prop size and/or recommendations for my Wellcraft...it has the 5.0L 200HP/V8 merc engine...picked this up pre-owned and put a 14.25R21 stainless 3 blade Rapture prop on it from my 17' Wellcraft - which i sold...since i swapped props (to keep the stainless), i don't know what was originally on the 200 Classic...the 200 Classic is open bow, 19' 6" in length, 8' beam and weighs 2600 pounds...

i use the boat mostly for cruising...not sure if my speedo is off, but i only could get it to 42mph...the RPMs were 3800...i will try to use a GPS this weekend to check the speed...

any info/advice is appreciated...

R-

Ayuh,.... Welcome Aboard,... There ain't no listings that'll tell ya the original prop,...
That's why it's important to answer the questions asked in the "Read This First" in the stickies at the top of the forum,...

But,... Whatever prop gave ya that rpms, is Too Big,... Ya need less pitch,... I'd guess 4" less,...

 

[jestor68]

Re: Prop size question: 1988 Wellcraft 200 Classic, 200hp/V8 merc

The WOT rpm range you're looking for is about 4200-4600 rpm.

Figuring 150-200 rpm per inch of pitch change, it looks like an 18 pitch should work out pretty well to get you right in the middle of the range at about 4400-4500 rpm.

Mercury's selector recommends the Enertia 14.2 X 18. The Solas HR Titan 3, 14.75 X 18 will perform as well for way less. It calculates(based on current performance #s) 4600 rpm @ 47 mph, with a much better hole shot than the 21.

 

[hackr]

Re: Prop size question: 1988 Wellcraft 200 Classic, 200hp/V8 merc

thanks, guys...

i found this tool online and punched in numbers to get a pitch/diameter recommendation...it only works on XP or Vista, tho...

Castle Marine - Pitch Calculations

with a few iterations, this calculator recommends a pitch of 17 and a diameter near 15...give/take...what do you think?...as a reminder, i have a 14.35 diameter, 21 pitch Rapture stainless 3 blade prop on it now - with this, i am running 3,800 rpm and a max speed at 41-42...

here's the info i plugged in:

engine: mercruiser stern drive, 5.0L, 200HP v8; max rpm @ WOT3 = 4400-4800rpm
boat weight: 2600 pounds (per welllcraft)...factor in a full tank of gas (52 gallons) adds 300 pounds...add 500-700 pounds average of passengers (700 with 2 male and 2 female adults) for a total weight of between 3400-3600...
boat length: 19' 6"; approx 16' 6" at waterline (guestimate)
gear box ratio: 1.65-1

thoughts/comments?...i want to be able to run with overall good performance - cruising 3/4 of the time, 1/4 of the time pulling kids/teens on tubes/skis...

thanks for your thoughts and recommendations...