Got a new boat and dont like my HIGH 5 prop need advice

[jokergerm]

So i just bought a 1998 21ft MILAN from the origanal owner with 500 hours in great shape.

Anyways we took it out wakeboarding this week end, with 6 of us in the boat. It gets out of the whole OK but not great. I have the high five 5 blade 19P prop on it. I can go 50mph with 3 people in it and 45mph with 8 people.

My question is what i can do to get to 60mph? maybe a 24p prop. because right now with the 19p at WOT i am at 4400rpm.

Also what kinda prop should i run for wakeboarding? i have a spare 17p prop that came with the boat. maybe get a 14p for boarding to get out of the whole?

Just looking for info on props.

PS the boat has a mercrusier 5.7. and alpha one out drive

thanks

 

[erlindbl]

Re: Got a new boat and dont like my HIGH 5 prop need advice

That high five propeller was designed for water skiing. It should give you an excellent hole shot and should pull your arms out of the socket when skiing. It is not designed for top end. Wakeboarding takes considerably less effort than skiing when getting pulled out. You should have no problem wakeboarding with that prop. You definately don't need to go down to a 14P.

As for top end, I'll let the others with more expertise in that area chime in. The fact you can do 50 MPH with that prop is pretty impressive.

 

[jokergerm]

Re: Got a new boat and dont like my HIGH 5 prop need advice

i mean its not too slow out of the hole, however i am new to wake boarding.

My friends cannot hold on to the rope tight enough to get out of the water. LOL

However, i am strong enough to get up. How does one determine how fast it gets out of the hole? Im sure the 6-7 people in the boat does not help either.

whats the max RPM on a mercrusier 5.7?

do you think i can hit 60mph with a 3 blade 23 or 24p prop?

I guess i was wanting the boat to just jump out of the water LOL

 

[Silvertip]

Re: Got a new boat and dont like my HIGH 5 prop need advice

You are not understanding how pitch affects power. Because some folks can't hang on tight enough does not mean they would be able to hang on with a different prop. If changing props allowed you to do that, that would be an indication you indeed have the wrong prop. 4600 - 4800 is tyical WOT rpm for your engine. You are already about 400 RPM under the ideal upper end of that range but that's likely due to the fact you are lugging around 6 people. The next thing you need to understand that when you go up in pitch you lose 150 - 200 RPM for every inch of pitch. Going from a 19 to a 24 is change of 5 inches of pitch which would lower RPM about 750 - 1000 RPM which will seriously impact hole shot, you will not get to 60 and in fact might not even get to 50 since the engine will not have enough power to twist that much prop. The prop is the transmission for your boat -- and it only has high gear. That's why prop selection is so critical. It needs to get you out of the hole yet allow the engine to operate in its RPM band.

 

[jokergerm]

Re: Got a new boat and dont like my HIGH 5 prop need advice

Ok with that said, what kinda of prop will give me more speed??

 

[Silvertip]

Re: Got a new boat and dont like my HIGH 5 prop need advice

Thought I just did that! You are asking for more speed and better hole shot. You can't have both. You need less pitch for hole shot and towing. and you can't go up in pitch because the engine is not reaching the top end of the band with the prop you have. You have a choice, go down in pitch or put your passengers on a diet. Here's my suggestion. 1) make sure the engine is properly serviced and tuned. If an engine is not making full power you cannot make up for that with a different prop. 2) determine what your average load is WITHOUT towing anything or anyone. If that's six people, you need to prop the boat so the engine can get to 4600 RPM at WOT. You can't do that now so you have one choice -- drop down in pitch and stay with the same design prop. You may pick up a tad bit of speed but don't count on it. The advantage is that you gain hole shot, speed stays the same and engine RPM gets where it needs to be. There is no free lunch when it comes to props -- the engine and drive delivers just so much twist. The prop transfers that twist to forward motion. Slapping a high pitch prop on a boat that can't twist what you have will not gain you any speed. That is unless you leave all your passengers at the dock. And for darn sure it won't do towing worth a hoot.

 

[jokergerm]

Re: Got a new boat and dont like my HIGH 5 prop need advice

Ok i just took the boat out, and at i am at 4500 rpm. With my high 5 19p prop. at exactly 50mph.

The top of the motor states Max rpm at WOT is 4200-4600 its a non vortec 5.7

I know i am beating a dead horse here. but what would a 21p 3 blade prop do? drop me down to 4k? at WOT. and give me a few more mph?

I have a set of vortec heads in the garage, could i swap those out and get a 4bbl carb and intake and hit 60+ mph? maybe more? i am guessing that swap would give me 60+ hp

I am going to swap my high 5 17p on today and see how she does out of the hole.

 

[redfury]

Re: Got a new boat and dont like my HIGH 5 prop need advice

Seems to me that you are hell bent on hitting 60mph. Bragging rights? There's no practical purpose of being able to do 50 or 60mph unless you are talking about traveling distances at WOT and want to cut down your travel time. Does not sound like that is the use you bought your boat for.

If you want more speed or power out of the hole, you need to get a bigger motor or have the one you have enhanced. If you put too big of a prop on the boat and can't hit your top RPM's, what's the point of having the bigger prop. Theoretically a larger prop means that the boat could hit 70mph, but add the weight of the boat and friction/drag and you'll limit that larger prop to what nature is going to let it do. You can't squeeze blood out of a turnip.

Get the prop that gives you max RPM/performance that is right for your boat and it will thank you later in lower maintenance costs.

 

[codertimt]

Re: Got a new boat and dont like my HIGH 5 prop need advice

Ok i just took the boat out, and at i am at 4500 rpm. With my high 5 19p prop. at exactly 50mph.

The top of the motor states Max rpm at WOT is 4200-4600 its a non vortec 5.7

I know i am beating a dead horse here. but what would a 21p 3 blade prop do? drop me down to 4k? at WOT. and give me a few more mph?

I have a set of vortec heads in the garage, could i swap those out and get a 4bbl carb and intake and hit 60+ mph? maybe more? i am guessing that swap would give me 60+ hp

I am going to swap my high 5 17p on today and see how she does out of the hole.

What kind of load was that 4500rpm with? If lightly loaded, then the 17P high 5 will be a better match when you load back up with 6 folks. IMHO, no reason to go buying more props, at least for the wakeboarding part. If you could go demo a few props you might find something better, but the 17P high 5 seems like it should be a pretty good match for the application.

That being said, as the other guys have mentioned, getting a good pull for wakeboarding with a full boat is a very different application than shooting for 60mph lightly loaded(which BTW, if you look at 21+ bowriders on boattest.com, you will see none of the approach that mark. Even the faster ones are mid 50s). I completely understand the desire for speed. When I got my new little Glastron, I was hoping for 55. Managed 53.4 all by my lonesome, but when we actually had people in the boat and I tried to slalom, the desire for speed was replaced by the desire to not be dragged behind the boat for 15 seconds before getting out of the water. Dropped some pitch and went to a 4 blade and now it pulls much better. I'll never be north of 50mph again, but I've come to accept that.

That being said, and this is pure conjecture, but I personally would guess a 21" 3 blade would actually not drop your rpm too much if at all coming from the high five. You very well might be able to spin it well enough to see mid 50s. But it would very counterproductive to you're wakeboarding desires, and as other have said, only really useful for bragging rights...or possibly outrunning an approaching thunderstorm.

Also, couple of other things I wanted to mention. You might want to check out some wakeboarding tutorial vids. Either buy one or look online. If you're friends aren't able to hang on, either they're doing something wrong in the water or the driver is being too heavy on the throttle. Both of which should be addressed in a good instructional vid...

Lastly, if you really hate that 19P high 5 and want to throw it out, I can give you my shipping address and you can throw it my way. I could even give you a 23P Aluminum prop in return...HA!

 

[jedimaster]

Re: Got a new boat and dont like my HIGH 5 prop need advice

You are doing 50 with a 5 blade 19 pitch?
Put on a 21 pitch 3 blade stainless with high cup and high rake, and you may hit 55 ish.you will drop about 200 - 400 rpm's.
Its really hard to say what the drop wil be exactly because your changing more than one variable. number of blades and the pitch.

But good luck pulling up a slalom skier.

3 blade for top end
4 blade for hole shot
5 blade to rip the handle out of your weaker skiers hands

with my bow rider and a 140 mercruiser, I could pull up a skier, or waker boarder with a 17 pitch alluminum 3 blade no problem.

 

[jokergerm]

Re: Got a new boat and dont like my HIGH 5 prop need advice

Ok first off you must understand who i am. I am 25 and i love to go fast in everything. Is it practical. NO do i need to go 60+ on the water No, Do i want to F*** yea. I drive a lifted 06 duramax with 700hp/1200 Foot pounds of torque. Some may ask, why do you need a lifted truck on 37's to pull a 13 second 1/4 mile. Because i can.

Anyways, i want my dam boat to go 60+, i dont really care what it takes with in reason. I have set of vortec heads in my garage and a marine holley 4bbl carb, if a get a intake for the 4bbl will the motor have the power to push a 21 or 22p prop to 4500 rpm? or is the prop going to lower the rpm no matter how much HP i give to it.

Today i tried the 17p, the boat literally jumps out of the water. and tops out at 42mph at 4900 rpm.

Since i am new to the boat world i just want to know what i have to do to make the dam boat stupid fast. since i have the heads and carb already and i know how to do the swap, will it work.

thanks

Im sure you all think i am a moron, but i like to go fast.

 

[jedimaster]

Re: Got a new boat and dont like my HIGH 5 prop need advice

Ok, so assuming your current numbers are right(are you using GPS or the speedo?

17 pitch prop
1.62 gear ratio
4900 rpms
42 mph
means you prop slip is .13
Thats a damn efficient hull..in the speed boat range
Anyway to move one.

In order to hit 60 mph you will need to be running 5680 rpms with a 21 pitch prop.
Best thing to do is get a most kick @ss prop you can buy, get it blue printed. Then figure out how many more RPM's you need and start adding horse power.

Prop slip calculators can't lie.
A prop can only push water and the boat as fast as the pitch.
EG a 17 pitch prop will move forward 17 inches for one RPM.
Your boat hull has drag and you prop has ineficiences.

Hope that helps you out on your quest.

I would think vortec heads, New intake, ported and polished, massive carb, direct through hull exhaust, and a blueprinted prop and you will be on your way.

JMHO

 

[jokergerm]

Re: Got a new boat and dont like my HIGH 5 prop need advice

HEY! finally i am getting some where.

Ok my question is the motor says 4200-4600 max rpm at WOT.

How the hell am i going to get to 5600 rpm? change the cam also? or is the 4200-4600 based on the stock pitch prop not allowing it to rev higher>?

5600 seems to be alot of rpm.

seems like its gonna be a challange to get to 60+

with those power upgrades is the 21p the best choice prop or should i stick to the 19p.

who makes good thru hull kits?

also do the high flow exhuast manifolds really help out for 500 bucks?

 

[1976 Slickcraft]

Re: Got a new boat and dont like my HIGH 5 prop need advice

5600 rpm`s with a 21-23 pitch prop on a 21' V hull. Is a good way to break an Alpha.
Jesse

 

[jedimaster]

Re: Got a new boat and dont like my HIGH 5 prop need advice

Thats just it, How are you gonna spin 5600 rpms's? Basicaly your not. I would think your gonna have to gain about 200 horsepower. And just like in a car if your running a 7 1/4 peg leg differential you will snap the rear end. Go for the big posi right? Same goes for boats. An alpha isn't designed for that much rpms and horse power. Gonna need to go with a bravo. Not sure what the gear ratio is or even if you can just swap them out. I think its a massive job. You may be better off just selling the boat and buying one with a big V6 Outboard. They have much higher rev ranges upwar of 6000 rpms and a 250HP can easily push a boat well beyond 60 mph.

For example my cousin has a 21 foot allison X2003 seats 5 people is a fish and ski model and he runs a 225 yammy with all the fixins....blue printed 28 pitch prop, low water pickup jack plate etc... and he just GPS'd i last night at 89.4 mph

I would think even if you were to convert your existing boat from an IO to an outboard you could hit 60 no problem with a 250 outboard.
PUll the motor, get new controlls, fill the hole in your transom, bolt on a jack plate and hook up your outboard and your off to the races.

HEY! finally i am getting some where.

Ok my question is the motor says 4200-4600 max rpm at WOT.

How the hell am i going to get to 5600 rpm? change the cam also? or is the 4200-4600 based on the stock pitch prop not allowing it to rev higher>?

5600 seems to be alot of rpm.

seems like its gonna be a challange to get to 60+

with those power upgrades is the 21p the best choice prop or should i stick to the 19p.

who makes good thru hull kits?

also do the high flow exhuast manifolds really help out for 500 bucks?

 

[tmh]

Re: Got a new boat and dont like my HIGH 5 prop need advice

joker, you need to ask the engine questions in the engine forum not the prop forum. 60 mph with your boat is not happening with a prop change - only an engine change or major mods.

btw, I think we all already understood "who you are"........not overly impressed so no need to push it down our throats. You aren't the first 25 year old that thinks he's super cool going fast, believe me.

Bottom line is you bought a boat not designed for that speed so if that;s your goal why not buy a boat that's made for it?

Also, get stronger friends. It's no feat of strength to get up on a wakeboard!!!! Little kids do it all the time!

 

[stinger222]

Re: Got a new boat and dont like my HIGH 5 prop need advice

I have vortecs on my 383 stroker and the torque is awesome, gets on plane instantly with a 20 pitch 3 blade prop. I can have 6 people on the boat and it gets on plane almost as fast as when it is just me. But the top end is around 55mph, which is fine for me, but I would get some Dart Iron Eagle heads if I were you and looking for the top end. The out of the hole is not as good, but the top end was low 60s with passengers, 65 with just me and fuel. I had a pair on my last engine when I was in my 20s. my boat came with a high 5 also and I switched to 3 blade mirage, helped the top end.

 

[tmh]

Re: Got a new boat and dont like my HIGH 5 prop need advice

stupid fast.

Guys, having re-read this thread I think there should be some concern with helping this kid go 60 mph in a boat. I see no signs that he is ready for that kind of water speed from a safety standpoint. It appears he and his buddies don't even know how to operate a boat to get wakeboarders up which is very easy to do (not easy to ride wakeboards great, but easy to get out of water without having the rope pulled from hands).

The swear words on a forum like this add to the picture of some almost drunk kid hauling 60 mph thru a no wake zone with his thru-haul exhausts blasting! Sorry, but that's my read on this thread. If I'm wrong, great - please site the boater safety course you completed, joker.

Boating is dangerous and much more so the faster you go. Before going 60 mph you need to learn how to handle a boat. Obviously, you're new to this, which is fine......just take things a bit slower until you are closer to an expert. keep your high five, go have fun cruising around 35 mph, do some ater sports with your buddies (or better yet find a girl) and have fun learning to boat safely and at safe speeds for a beginner.

 

[jokergerm]

Re: Got a new boat and dont like my HIGH 5 prop need advice

wow its people like you that really **** me off.

On here I said nothing about Hulling *** threw a no wake zone or being unsafe.

Then you try and attack me because my friend could not get up on a wake board on his first day out? Sorry he is not a PRO from day one, That must mean that i cannot operate my boat properly and safely.

And I am not trying to go fast to be cool either, i do it for my own self gratification, and enjoyment.

I have been on boats my whole life, and lived on a boat for 4 years. Sorry that me wanting to go fast make me a stupid dangerous young kid. Well that's not the case. There is a time and a place for everything buddie.

I'm pretty sure if i was just a stupid young kid that did not care about safety and follow rules i would not own 2 restaurants free and clear at 25.

So don't jump down my throat unless you know what you are talking about, and don't try to FAB some story up about who i am because your an over analyzer.

 

[K.P.]

Re: Got a new boat and dont like my HIGH 5 prop need advice

You just come across as a punk to me. And as long as you have supposedly been around and living on boats you obviously were too self absorbed to learn anything about the performance dynamics of boats. I'm sure safety was even less of a consideration.

You are getting some of the best advice you will find on this board but as long as no one tells you what you want to hear, you will not listen to what you are being told.

Obviously you are Mr. Big Wig with two restaurants and tons of cash. So go buy yourself a twin drive Baja and head to the ocean or great lakes. At least you'll be less of a danger to those of us that have some appreciation for safe boating and a low tolerance for Punks.