prop pitch question

[T-water]

hey folks

I've got a 30 hp Honda 4stroke tiller on my 16ft lund. The boat is similar to to ssv model (like the ones you might see at a resort). Ive got it decked out with casting decks and stuff...the problem is I cannot get it on plane when I have 2 people in the boat, I've figured out its due to needing a different prop.

Currently I have a 9 3/4, wondering what I need to change to as well as were would be the best place to buy it?

[Wade Joseph]

9 3/4 sounds like a diameter. What you need to find out is the "pitch". Theoretically pitch is the distance the propeller would travel thru the water with zero resistance in one revolution. IE...a 17 pitch prop would travel 17" thru the water. If you take the prop off you should find both the diameter and the pitch stamped on the prop hub somewhere something like "9 3/4 x 15". You also must be conscious of rpm. Your motor needs to run in the mfg recommended rpm range at Wide Open Throttle. This can be found in the manual or call your dealer and ask. You may need to get a prop that 1-2 inches greater pitch to get it on plane. Is your current prop aluminum or stainless? Stainless doesn't flex as much as aluminum, takes a little more abuse in gravel and sand than Alum but costs alot more. There are also Composite props available that will sometimes be a better option if costis a factor.

So, lets say your prop is a 9 3/4 x 15, your motor is running at 5900 rpms WOT. The recommended range is 5500-6000. If you put on a 17 pitch stainless, your rpms will drop aprox 400 (200 rpm per inch of pitch is a good rule of thumb) but you should get on top better. DO NOT go gelow the mfg recommended WOT rpm as you can damage your engine.

If tyou can find out these things, cabelas has a good selection of props you can order.

[Fishing Junky]

What year is your engine? Does it have tilt and trim?

[T-water]

Thanks for the replies. The motor is a 98, the pitch is 12 (sorry about that). Tilt has not fixed the issue. I'm actually heading to cabelas tom. Is there a recomendation for a ballpark pitch that should work without being detrimental to the engine? I'd rather do it myself and don't have an rpm gauge. Wade Joseph what is WOT? I'm guessing wide open throttle????

Any feedback would be great.

[Wade Joseph]

Yes, WOT is Wide Open Throttle. I guess without a rpm gauge, and now knowing your current prop is a 12 pitch (Aluminum I assume), I'd go with a 13 or 14 pitch stainless.

[upnorth]

If you are having problems getting on plane I would drop the pitch by one or two. You will lose abit on the top end but it will get you up on plane better.

[Fishing Junky]

In my opinion, a 12 pitch on your boat setup sounds about right to me. The boat in my avator is a 2006 Lund classic 1625 tiller. I have a 2006 30hp Honda w/tt on it. Mind you, I only have an hour and a half on the boat, as I bought it last October. I highly doubt that your boat wieghs more than mine. There is a 12 pitch prop on my motor. With just me, group 27 battery in back and two seats, and a lifevest on board, my rev limiter would kick in at wot, with the engine trimmed half way up. Trim a hair down, and all was fine. Mind you, I had no weight in front. I guess my point is, that pitching down, may or may not over rev your motor. When trying to get on plane with two in the boat, is your problem plowing water, or can't get your bow down? Often times on these smaller lightweight boats, shifting weight in the boat often helps. Especially when you don't have tilt and trim. That's a heavy motor on the back and not alot of boat in front of it to help get the bow down. Before I bought any prop, I would raise the motor up one hole and shift some wieght forward if you are having probs getting the bow down, or move some weight back if your plowing. Just my opinions, so take it for what it's worth. If you want to go stainless though, I HIGHLY recomend a Turbo Hot Shot prop. They are designed for our type of applications. I've owned one, and it was a great prop. (16ft Lunker w/25 Yamaha). Good luck and I hope I gave ya some ideas. Junky....

[primetime49]

9 3/4 by 11 on my honda,had sme problem with a 9 3/4 by 13.

ask a Honda lund dealer,rigging shop.Rapid Sports Center has sold these for years.

[T-water]

Thanks-

I talked to a good guy at cabelas today, he reccomended I drop to an 11, course they didn't have the prop in stock, but I'll try to get it onine or at a local shop. I'll let you know.

[crappie todd]

look on the boat sticker for maximun motor HP and max weight with all gear and persons. I doubt you have enough outboard HP for the boat size.

[T-water]

The max motor size is 40 hp. It's not real big, should be able to get on plane, I did get up with my olpd 25, I thought the 30 was just too heavy. We'll see.

[crappie todd]

I should have read closer as I see you have a 4 stroke, 30 HP. That explains a lot. I have owned rigs where I bought the motor that was on the boat. Usually always under powerd. Then I went to buying what the max motor HP was based on the boat sticker rating. I bought new rig two years ago with a 60 Hp four stroke. I love the gas milage, I love the smooth quietness of the motor. But what I did realize was the low end PUSH to get up on a plane is compromised by the fact it does not wind out as quick. Getting up on a plane is slower.

The boat originally was being sold with a 50 Hp motor. The max was 60 and I am glad I got it because the 50 would have been more disapointing. Trim makes a difference as well being " tucked " under when taking off then triming out.

A lower pitch prop will help you./ But do watch the top end RPMs.

[glendam]

Crappie Todd, What size prop do you have on your 60 hp? I have a Yamaha 4 stroke 60hp with a 10 7/8 x 11 on it and am thinking that its a little small, my rpms @ wot are 5900

[Northlander]

Give Jay Soderbloom a call and he can tel ya what you will need and he can set ya up with a the right prop at a good price. Plus he is a FM sponsor. www.soderbloom.com

[T-water]

Thanks Northlander-

Consider it done!

[crappie todd]

My prop is stock and I think it is what you said in your post. I can get up alright and top end is 38 mph which I am pleased with. My rig is up north so I can't verify the prop right at the moment.

But let me ask you another question: do you have any cold start problems.? Mine is difficult though once going, I don't have a problem unless I let it sit over night.

Other wise I like the gas milage and it is quiet.

Mine is a carb. wished I had waited for the new EFI version.

Though I had a 99 evinrude 50 Hp EFI four stroke and it would vapor lock on hot days. I got rid of it for that reason.

[glendam]

Crappie Todd, I have the fuel injected 4 stroke and it fires up every time. What kind of boat do you have? My boat is an Alumacraft Navigator 165 and my gps has yet to crack 30 mph. It could have something to do with it being 90" wide and 2 batt. up front, but I thought that it would go over 30 mph! Thats why I was wondering what your prop size was.

[crappie todd]

Glenddammit: I have a 16 ft lund SS. 90 inch wide. but I have remote steering. The boat it rated for 60 HP max. I have front trolling motor with battery up front. Rear trolling with two batteries in the rear and a 18 gallon gas tank in the floor.

I raced my old boat that had a 50 Hp evinrude and was about equally matched except it was a tiller. The 50 beat me out of the hole but I could catch up eventually but could not overtake it.

Wish I had waited for the EFI. but I know they run alot more $$$$. I have had it for 2 years this June. I typically fish alone so its not really an issue. the lake I fish is 700 acres, so the 60 is plenty.

[Fishing Junky]

I'll be the first to be suprised if you prop down one pitch helps your situation, UnLESS IT IS A STAINLESS PORP. If it does great, but if it doesn't, check out my previous post. I hope it does work for you, Junky......

[crappie todd]

fishing junky. the stainless have less flex.? The cost difference has to be pretty hefty. But the performance has to be extreme on the positive side. so what is it that makes it the choice to help get an underpowerd rig up quicker.?

[Fishing Junky]

Quote:

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fishing junky. the stainless have less flex.? The cost difference has to be pretty hefty. But the performance has to be extreme on the positive side. so what is it that makes it the choice to help get an underpowerd rig up quicker.?

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Hey Todd. For one thing, I don't think his rig is under powered. I guess that depends on how fast he wants to go. How much does the operater weigh? How bout the guy in front? In my opinion, his boat should go pretty nice with that 30 Honda with 2 guys in it. BUT, I asked a question that the poster never answered. Does he have a prob w/plowing, or does the bow not want to go down? My guess is the bow will not go down. Been there, done that. Does the person in front, have to stick half his body in front of the boat nose to get the boat on plane? These are the questions that I need answered to give this man an honest answer to his question. Stainless would defintely help this guy in my opinion, BUT I bet if he raised the motor one hole, and stayed with his 12 pitch prop and put some weight in the front (50lbs), His prob might be solved. BUT, it's hard to say without answers, and it's even harder to say without being there to help. Here's my solution. IMO of coarse. Raise the motor a hole with the same prop. Does it help? Yes, problem may be solved. Or talk with Jay and go with a 12 pitch Hotshot prop and that will give you more rpm's and better prop bite and even better holeshot. No: Go with mentioned props and shift some weight, or put a 50 or more sandbag in fron of boat, OR go with an 11 pitch Hotshot prop and see what happens. I guess I need more info to help, as I've had more BWCAW boats than a man deserves. Let me know, Junky..........

[T-water]

Junky

I've tried moving the passenger and the motor..to the point of exhaustion. Really didn't change much, didn't plane. I'm a 250 lb guy my passengers range from 150 -200. I currently have a 12 inch prop. Looking forward to more thoughts, I'm stuck in a week-long conference and don't have acces to internet/ability to call folks during the daytime so my attempts to resolve this issue will begin on Monday. I didn't mean to blow off your suggestion I just know that my attempts were frustrating, and I'm looking for a final answer

[FishdogCo]

Judging from the prop size and pitch, and the sze of the boat, you should ave no issues getting on plane. Just a thought that I offer to share, I see that the engine is a a few years older. Have you changed the plugs and blown out the water separator? I know it sound a little nutty, but I had almost the same issue this spring with my 17' Lund with a 140 4-stroke on it. Engine purred like a kitten, no miss, no knock, but could not get the boat to jump up on plane. Returned home, swapped out the plugs for new and that engine "woke right up". For about $10.00 for a set a plugs, it might be worth a try.

Regarding the Stainless Steel prop, you get very little flex out of the prop which in turns gives you less cavitation and more "bite". Everything being equal, I picked up another 9 mph and an awsome hole shot moving to a SS prop of equal pitch and size. Just remember, if you strike something with a SS prop, you damages gears and lower units, the prop does not bend. They are a bit pricey but well worht the investment. There are some prop calculators out on the internet that you may want to check out as well. Those should confirm your prop size and pitch for the load.

If all that does not work, I would suggest calling the engineers at Michigan Wheel in Grand Rapids Michigan. They manufacture about 80% of the props on the market for recreational use. They will NOT sell you a prop, they are a manufacture only, but they are great to work with in getting the right prop dia/pitch based on your boat size. engine and load.

Mark

Team Fishdog

[crappie todd]

I have had big boats, I have had small boats. been in between all the HP ranges to the final match of boat fully loaded to my self in the back @ 300lbs.6 rigs since 1979. many mistakes. I agree that even under powerd the boat should eventually plane out. I did the old shift my weight forward, put weight up front. and re propped to a lower pitch. So I will stop the argument of being under powerd.

So now I ponder.... Is the motor in need of a WOT adjustment. I know he should be able to take a peek by removing the cowling and advancing the throttle with the engine off and seeing if it bottoms out at WOT. And he msut have tried adjusting the tilt.

I feel this guys pain. There must be a marine expert on here that can tell us what the hecks going on.

be interesting to see how this is resolved. I will just follow the thread from here on in and keep quiet.

[Surface Tension]

Before you go out and buy a prop do what Fishing Junky suggested.

Moving the weight around in the boat is going to have a greater effect then a different prop. You have a small outboard, you can't expect a prop to overcome improper weight distribution. It might be as simple as having the passenger sit in a forward seat till you get on plane. Once there they can move back to get the bow from plowing.

Not having T&T, you'll want to experiment with motor hight and then make a compromise for best hole shot and cruising.

Do the above and then once your able to get on plane then you can determine if a different pitch prop might improve things. What to look for is excessive or low RPMS at WOT. Again that shouldn't be considered till you get your weight distribution and motor hight figured out.

[upnorth]

I have no direct experience with them but the hydro foil/whale tail things are supposed to help a boat get on plane. I know a couple guys that have em and they say they help with both getting up on plane and help some handling issue.

[T-water]

Thanks guys,

Again I've tried the tilt and shifting the passenger around deal-very little impact...I'm not sure what I'm gonna do next, but I'm having less confidence in the idea of changing the prop...I haven't tuned it up for a while, last 2 years been fishing without my boat. Sometimes ignorance is bliss I plan on calling around for a few ideas tom. but most boat dealers I talk to say I need to change the prop, I know I'd be very bummed if that didn't work.

[minneman]

Quote:

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Ive got it decked out with casting decks and stuff...the problem is I cannot get it on plane when I have 2 people in the boat

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Did the boat plane pryer to the casting deck install?

and what other "stuff" is adding weight?

I did the same to my 16'er/35 merc 2 stroke. added the deck and after that the thing would take forever to plane, it had a 13 pitch and I switched to an 11 and it made a huge difference, WOT was only about 20-21 mph gps w/2 in the boat, but the hole shot was much improved.

[marine_man]

Quote:

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Did the boat plane pryer to the casting deck install?

and what other "stuff" is adding weight?

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These are both good questions.

And, this may be a stupid question on my part, but when you say you tried the trim thing, you've got the motor trimmed down all the way when you take off right? I think you're going to need to drop prop pitch to get your boat out of the water.

marine_man