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Post by mapper on Sept 15, 2023 19:46:41 GMT -5
I'm looking for better holeshot on the 1900xs nauticstar. Full fuel tank, but just me, so I'd usually have a cooler, and fishing gear, and another person.. 17 pitch prop 5500 rpm 41 mph on boat speedo
I bent that mutha coming in, so got a 15 pitch I haven't tried yet..
So here is the question.. is a 4 blade stainless prop worthy of consideration? I'd like good holeshot , midrange and load carrying.. Yes it's a heavy boat..
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Post by mapper on Sept 15, 2023 20:00:54 GMT -5
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Post by Crkr 23 on Sept 16, 2023 6:51:15 GMT -5
I prefer 4 blades for all the reasons you mentioned.
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Post by cadman on Sept 16, 2023 7:25:18 GMT -5
Lower pitch, more blades, faster holeshot
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Post by mapper on Sept 16, 2023 17:27:25 GMT -5
Ok, going from 17 to 15 pitch, adding extra person in boat seemed to help holeshot a little. Lost 4 mph, gained 300 rpm or so wot. That's a "made in taiwan" prop..Yamaha prop selector shows 14 and 16 pitch choices in turbo fx4, yam performance data shows 2 people 1/2 tank fuel, 3 blade performance stainless 16 pitch prop.. My testing was full of fuel and 2 people.. 5800 rpm, 35 mph gps and speedo.. 15 pitch or 5500 rpm, 40mph, 1 person 17 pitch speedo no gps
I might have to ask the propgod, lol.. Chart shows wot range 5000-6000
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Post by saltybum on Sept 17, 2023 15:10:48 GMT -5
A hydrofoil can help a lot to keep the nose down for better acceleration and reduced bow hop in choppy seas. Plus they DON"T cost $400-500
With the 17 prop you'll get the higher end speed too. Just a thought here.
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Post by mapper on Sept 18, 2023 17:34:31 GMT -5
I'll check cavitation plate height next time I go out and make sure no drag. If so I'll raise motor a hole or 2. I picked up a doel fin to try as well. I might look at 4 blade prop after that. But it still won't be a speed demon no matter what. It is what it is
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Post by mapper on Sept 19, 2023 18:25:29 GMT -5
Ok, put doel fin on, seems to help come on plane quicker. A bit touchy at high trim angle. But didn't lose or gain speed. 5800 34.5 mph, 5000 29 mph. I'm hoping a little tweak of a stainless prop would give a little more holeshot and thrust. Without giving up any speed.. I think I'm going to have to raise motor a hole or 2..
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Post by 1outlaw on Sept 21, 2023 10:47:05 GMT -5
Do not raise motor if you dont have a water pressure gauge. You currently know it doesnt over heat or run hot. Raising motor could effect water pressure.
As for prop changes. Typically you drop 1 pitch when going from a 3 blade to a 4 blade. Your mileage may very depending on prop make. They arent all the same.
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Post by tonyroma on Sept 22, 2023 18:16:55 GMT -5
You went from 41 mph to 34 at 550O RPM? I have a 115 on a 19 ft bay and I can’t touch that.
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Post by mapper on Sept 22, 2023 19:48:03 GMT -5
34 mph 5800 gps verified 15 pitch..
41 mph at 5500 17 pitch not gps verified. Just speedo-lie-o-meter.
I think answer is raise motor up until cav plate runs jut on top of water,( currently it runs just underwater) and hope I can get decent numbers then to see if a 15 pitch 4 blade stainless would work, or whether a 14 pitch..
But the lack of water pressure and trim guages.. I will make sure at neutral trim water pickups are covered though . I've got a water pressure and trim guage coming.
Ive been busy with getting my street rod back..1948 Chevy panel van. It needs sold., car trailer as well.
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Post by 1outlaw on Sept 25, 2023 10:44:43 GMT -5
You went from 41 mph to 34 at 550O RPM? I have a 115 on a 19 ft bay and I can’t touch that. My 19' Blazer bay boat runs right at 40 WOT with a 115 yamaha. Thats GPS BTW |
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Post by mapper on Oct 25, 2023 12:07:27 GMT -5
Raised motor up 2 holes, added trim guage and water pressure guage.
6000 rpm, 37.5 mph loses grip past 3/4 on trim guage
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Post by james14 on Oct 25, 2023 16:19:37 GMT -5
A few things:
An aluminum prop will flex some, causing an increase in RPMs.
A 4-blade does give some more lift and helps heavier boats handle better. They don't have to be slower - mine isn't - but the extra blade causes less prop slip (more bite) which means you go lower on the pitch to achieve the same RPM.
It seems that a 6mph drop with a 300RPM rise at WOT is a bit suspect with only a 2" drop in pitch. Have you run those numbers through a prop slip calculator?
Trying to guess and figure it out yourself can be a waste of time and money. If you're going to buy a new prop, just contact one of the companies to help you narrow it down. It didn't cost me any extra to have PowerTech recommend a prop and they just about nailed it.
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Post by mapper on Oct 25, 2023 16:46:34 GMT -5
6000 at 37.5 mph WOT
I still need to play with the trim tabs a little this was no tabs. |
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