Newbie Needs help proping my 96 four winns volvo penta 3.0

[4winnsskipper]

Currently have a 170 horizon open bow four winns, 3.0 volvo penta, 4 blade, SS stilleto 22 pitch. Boat runs around 4100 rpm at WOT around 38mph. Takes longer than i would expect to get on plan, and not good at pulling tubers/skiers. I was looking at dropping down to a 17-18 pitch...but how many blades? 3? 4? 5? SS or aluminum? The boat does see shallow waters but nothing really rocky, mainly sandy and muckey bottoms in the shallows, not rocky. Advice? Would i gain MPH since i'd be higher in the revs?

 

[WillyBWright]

Re: Newbie Needs help proping my 96 four winns volvo penta 3.0

You can have your current prop repitched to a 21, maybe a tad lower. That would get you more revs and better holeshot. You might also consider getting a regular 3-blade aluminum as a spare if nothing else. I'd say a 19p. I think a 17-18 would be a bit too low.

 

[tmh]

Re: Newbie Needs help proping my 96 four winns volvo penta 3.0

Well, you are on the right track, that 22" is just too much for that engine. What to get depends on what activities are most important to you, as props are all a "compromise" of sorts. With a 3.0, you lack power to overcome some compromises, so you may want two props, one for water sports (pulling) and one for just cruising or going fast. You need a backup anyways and changing props is pretty darn easy IMO.

My guess is a 19" 4-blade or high 5 would be best for tubing, etc. However, seems many 4-blades only come in even number increments, so maybe an 18". A 19" 3-blade may do best for cruising.

Now, before I made any final prop decisions, I'd put Smart Tabs on the boat. These can really help get you on plane FAST so you may be able to stay with a 3-blade 19" for everything. On my stern-heavy boat I went from maybe 6 sec. to plane to around 3 sec or less with the Smart Tabs. The boat just pops up. Nauticus can tell you which one to buy.

Good luck.

 

[4winnsskipper]

Re: Newbie Needs help proping my 96 four winns volvo penta 3.0

Any difference between 3, 4 and 5 blades??? if pitch was equal, which would plan faster, which would have a better top end, which would exert more torque upon the water, etc..... thanks

 

[tmh]

Re: Newbie Needs help proping my 96 four winns volvo penta 3.0

In general, more blades gives you faster planing and better low-end performance. High 5 prop I've read is great for water sports. All else being equal, 3-blade normally provides more top end speed. SS can provide better performance all around than aluminum, with added risk to outdrive, according to most folks.

So, it's all a compromise, based on what's important to how you use the boat most often.

I have a 3-blade SS prop for normal use, but also carry a 4-blade (lower pitch) as a spare or to put on if we're doing water sports all day. The 3-blade is OK for hole shot since I added the smart tabs, but not as good as the 4-blade.