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Old 12-31-2015, 09:17 PM   #121
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@willowb. There is a label on 'Slip Aweigh' on the helm hub that states the maximum diameter and cup size the boat should have. Does yours still have the label?? Do any other owners have such label? Is it different depending upon which engine was original?

No such label. I believe the PO(s) have tested, as I have a 4-blade wheel in my lazarette. Please understand, I haven't gotten Willow B home yet. The original sales documentation with the Perkins 4-108 engine indicate the 18 X 12 - 3 blade wheel as standard. But it also states 3000-3200 for an operating range for this 3600 rpm engine. Just my opinion, but that's pushing a little hard.
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Old 12-31-2015, 09:34 PM   #122
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Such a label on the hub of my lower station helm. Also, owners manual, original , states the wheel in place when vessel was delivered. Yes, it is my understand helm size was dependent on engine and gear.

We purchased our boat from the original owners and they had well preserved everything in the way of paper work etc. regarding hull # 6

I, too, have previous owner(s) who did a very good job at preserving documentation. I even have the original bill of sale as well as original loan documents. The rub is it is in Waukegan, Illinois with the boat and I am home 500 miles away.

As we are still ferrying the boat home, I am doing all this long distance. Instead of attempting to work out what prop (3 vs4 blade), pitch, etc... I'm gonna call the marina and ask them to pull the prop, add 1" of pitch and reinstall. I will fine tune the 4 blade and swap it out later once we get Willow B home.
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Old 12-31-2015, 09:54 PM   #123
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Yes but there are many other people reading the posts.

And one of the dificult things on TF is frequently not knowing the boating knowledge of the guy you're talking to. I thought you knew but many many boaters talk about throttle amounts as a percentage of throttle position or throttle travel. I'm thinking you were at least a bit offended. Please accept my appology.

Not offended at all! I do believe we are speaking apples and oranges. And we got fruit salad.

I'm not illiterate, but when I re-read my blog entries & posts, I gotta wonder.

Yeah, I'm gonna ask the marina to add 1" to current wheel & I will deal with fine tuning once the boat is home.

Thanks Eric

-Evan
Gotta find wife, 2 hrs 'til 2016
HAPPY NEW YEAR!!!!
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Old 01-01-2016, 11:08 PM   #124
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Does your prairie still have the engraved plaque with RPM and MPH listed mounted on upper console? ( at least that's where mine is). The max speed listed on mine is 9 MPH. That's 7.8 knots. Sorry. These fine vessels don't do more than that. If they did the Manufacturer would have 'made it so number one.' Not sure where you want to go with Willow B. But over 8 most likely ain't gonna happen no matter what you do to prop, engine HP or rpm.

I'm going to check up on boat Sunday. I'll try to take a pic of the plaque.

It's funny you mention the original bill of sale. I have that also. $118,000 for this little girl!
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Old 01-02-2016, 08:45 AM   #125
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I suspect the plaque is right. Very comfortable at 6, nice and smooth and quiet. Am presently completing a bottom job. We removed all the paint to the gel. Put back four coats of barrier coat, two coats of bottom paint. Putting on a new prop, four blade, 18x13. We will find what happens.

Also have original bill of sale, loan material, and first documentation. They took delivery in February 1978, hull #6, in Tampa, behind their house. Their first cruise was to the Dominican Republic, where they lived for three years. Delightful couple, they enjoyed their Prairie 29' This Bill of Sale was for $32,000.00

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Old 01-02-2016, 01:36 PM   #126
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Does your prairie still have the engraved plaque with RPM and MPH listed mounted on upper console? ( at least that's where mine is). The max speed listed on mine is 9 MPH. That's 7.8 knots. Sorry. These fine vessels don't do more than that. If they did the Manufacturer would have 'made it so number one.' Not sure where you want to go with Willow B. But over 8 most likely ain't gonna happen no matter what you do to prop, engine HP or rpm.

I'm going to check up on boat Sunday. I'll try to take a pic of the plaque.

It's funny you mention the original bill of sale. I have that also. $118,000 for this little girl!

I do not have the plaque on the console. I did see a review and sea trial results. They called 3000-3200 rpm cruise. So I dismissed their numbers as sales hype. I am only trying to get to 6.5-6.8k without pushing the little 4-108 too hard.
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Old 01-02-2016, 01:45 PM   #127
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Given all the circumstance and the age of the engine, I am really not interested in anything over 2700, just not worth the small gain. Once again,2500 to 2600 are sweet.
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Old 01-02-2016, 01:54 PM   #128
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I suspect the plaque is right. Very comfortable at 6, nice and smooth and quiet. Am presently completing a bottom job. We removed all the paint to the gel. Put back four coats of barrier coat, two coats of bottom paint. Putting on a new prop, four blade, 18x13. We will find what happens.

Also have original bill of sale, loan material, and first documentation. They took delivery in February 1978, hull #6, in Tampa, behind their house. Their first cruise was to the Dominican Republic, where they lived for three years. Delightful couple, they enjoyed their Prairie 29' This Bill of Sale was for $32,000.00

John

I agree with the comfort of 6. At 5.8k the 4-108 is running @ 2500-2600 rpm swinging a 18X12-3 prop. No vibration, with little noise in saloon. I am hopeful of getting to 6.8k with a prop adjustment.

What engine and prop are you currently running? Please post results of the new 18X13-4 prop.

I left all documentation onboard, but the $32,000 sounds familiar. The original loan was for $16,000, if memory serves.

Thanks
-Evan
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Old 01-02-2016, 02:29 PM   #129
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WillowB- Per our PM the formula from Vicprop for a four blade is 19.7 (20?) X 14.6 (15?) So if the
quote;
'What engine and prop are you currently running? Please post results of the new 18X13-4 prop.' is based on making the WOT goal, then the formula from Vicprop will result in a bit of 'Over Wheel". The nice result is running the engine at a lower RPM achieving the hull speed desired, and having a quite interior while cruising. That alone will increase your boating pleasure. There is a winning outcome.
The Perkins is a work horse cast iron tractor engine designed for torque.

Maintaining the rule of running at 3/4 of WOT RPM will satisfied engine life rules.
Hence, if you are running 2250 RPM now to obtain about 6 knots, then the larger wheel should allow you to obtain identical hull speed at 1600 RPM.

Big difference in sound level. Probably notice quicker response to slow (Docking) speeds as the wheel will take a bigger bite in reverse.

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Old 01-02-2016, 05:31 PM   #130
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Prairie 29 engines

Quote:
Originally Posted by Al View Post
WillowB- Per our PM the formula from Vicprop for a four blade is 19.7 (20?) X 14.6 (15?) So if the

quote;

'What engine and prop are you currently running? Please post results of the new 18X13-4 prop.' is based on making the WOT goal, then the formula from Vicprop will result in a bit of 'Over Wheel". The nice result is running the engine at a lower RPM achieving the hull speed desired, and having a quite interior while cruising. That alone will increase your boating pleasure. There is a winning outcome.

The Perkins is a work horse cast iron tractor engine designed for torque.



Maintaining the rule of running at 3/4 of WOT RPM will satisfied engine life rules.

Hence, if you are running 2250 RPM now to obtain about 6 knots, then the larger wheel should allow you to obtain identical hull speed at 1600 RPM.



Big difference in sound level. Probably notice quicker response to slow (Docking) speeds as the wheel will take a bigger bite in reverse.



Al-Ketchikan

I agree 100%!!! My biggest (and only) fear is that I throw too much diameter and/or pitch and the little motor struggles and can not perform in the strong currents I am sure to encounter.. Ordinarily no big deal, just re-pitch. BUT, the remainder of this journey home (1100 miles) is all rivers. And not little rivers, Mississippi & Ohio, so I NEED to not be too far over propped.

I am just under 6 knots @ 2500 rpm. Generally, 1" pitch=250 rpm... So theoretically, adding 1" pitch will net me 6 knots @ 2250 rpm. So that is where I'm gonna leave it until I get Willow B home, where I can start experimenting and dial it in.
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Old 01-02-2016, 05:47 PM   #131
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Willow,
Sounds like you need to be not over propped at all. Shoot for 3025rpm.
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Old 01-02-2016, 06:18 PM   #132
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3025 RPM??? Either Eric is desirous that your WOT be that or what?

You have a Corundum between the two of us. My position is with over wheeling to the formula that you received from Vic prop through me, or the information from the other Prairie owner who is close with the Vic prop measurements, you will have the advantage of torque in the river currents. Think tug boats- they turn large wheels with high reduction gears. Your 3:1 is middle of the gear ratio field, said as tug boats often turn 4 or 5:-1 gears.
With the ability to use the tongue you will maintain a steady force and still have a couple of hundred RPM were or should the case be. With a smaller wheel, you will be winding the engine up considerable saying that as 2200 RPM or so, is your current throttle to obtain around 6 knots.

This really is a ongoing discussion between Eric and I over many posts past. It is an enjoyable discussion. I on my side, have the actual physical being of my convictions with the results of our boats performance. Eric has his. The root difference of importance, (At least to me) is not having to listen to a high screaming engine noise, even with well insulated space, the high pitch scream is not a soothing atmosphere while on the water, or the thought of having to INCREASE THE RPM(and accompanying increased screaming) to make time against the tide or currents. The solid thump of the solid working engine at a low RPM gives me the confident comfort of peace and tranquility.
It will be interesting to have the outcome through your voyage, unfortunately, the thread and thoughts will be far down the pike before you make the trip.

Lots of time for further futile debate!!
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Old 01-02-2016, 06:30 PM   #133
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This seems to be the time I am glad I am overpowered. I am surprised at how slow the Prairie and Willard are.. With my 200 hp Volvo at 2000 RPM's and an 18x17 4 blade, I can easily cruise at 7.2 knots which feels to be the sweet spot, I have a 3600 WOT engine, so I am not stressing things at all, and may be running at a less than optimum RPM/% of max. So be it. at 2GPH and a big range of potential speeds up to 16 knots to deal with weather and tide conditions it seems to work fine for my boat (at probably 9500 lbs loaded)
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Old 01-02-2016, 08:06 PM   #134
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Al,
We can all prop however we want as these are just toy boats and we have no one to answer to.

As to noise and vibration those w big engines consider that bigger pistons, crankshafts ect make more vibration. A lower frequence I'll grant but still more. And less irritating too .. I'll also grant. But there are ways to deal w both vibration and noise.

And as to credibility just ask an engineer. Ask an engine manufacturer. Or ask Tony deAntoino who appears to be a member of TF now. And if you want a low rpm engine find one and put it in your boat. One of the engines I was looking at when I repowered Willy was a 2500rpm engine ... but it made too much power. And the engine in my previous boat was a 3450rpm Yanmar. And I cruised at 2750rpm.
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Old 01-02-2016, 08:25 PM   #135
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The prop I am swinging now is a 18x12,three blade left hand turn. The gear is a 2.9:1 BW. The new prop is a 18x13 four blade. The original manf boo for the owner stated she had a 18x3 three blade prop. That is what the previous owner told me he used till he switched to a 17x 12x 4 blades. Using the Vic prop guide and the service of the local prop shop, Canaveral Prop, very good shop. I am switching to the 18x13x 4 blades. The plan is to be in the water end of week and or early next week.

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Old 01-02-2016, 09:55 PM   #136
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John,
I've got a 2.57-1 BW driving an 18 X 13 three blade.
Sounds right.
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Old 01-02-2016, 10:40 PM   #137
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Quote:
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(at probably 9500 lbs loaded)
Heron- Given access to several posters with this boat, I would think your boat comes in nearer 11,000#. The Prairie is so close to our Marben in style, displacement and such. Out of the box the Marben weighs 10,000# and now with all that I have added in ballast and external items the weight is closer to 13,000-13,500# and could well be more than less. It is surprising how much weight moves on to the boat the longer you own it. Wait till you become a subject of 2-footits and you begin moving stuff off your present boat to the new one. Scary!!!

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Old 01-02-2016, 11:20 PM   #138
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Quote:
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This seems to be the time I am glad I am overpowered. I am surprised at how slow the Prairie and Willard are.. With my 200 hp Volvo at 2000 RPM's and an 18x17 4 blade, I can easily cruise at 7.2 knots which feels to be the sweet spot, I have a 3600 WOT engine, so I am not stressing things at all, and may be running at a less than optimum RPM/% of max. So be it. at 2GPH and a big range of potential speeds up to 16 knots to deal with weather and tide conditions it seems to work fine for my boat (at probably 9500 lbs loaded)
Just for the heck of it I ran your info through Vic prop to see how close. I did use 12000# as the weight.
According to the results, a 2 blade wheel would be 21X13.2
3 blade would be 20,3X13.1
and a 4 blade is 19.1x12.8

Using one inch in diameter equals 2 inches of pitch it would seem you have hit the bulls eye as the adjustment for that formula would have you with a 18X14.8 or rounded off 18X15. Pretty darn close which gives a bit of credence to the formula.
It has for me over the times used.

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Old 01-02-2016, 11:22 PM   #139
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Dosn't the Prarie have a 12' beam .... and I think the Marben is fairly slender.

With such a large difference in beam it would seem the Marben would be heavier .... and of course harder to drive. However it's possible they could be about the same displacement.
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Old 01-02-2016, 11:40 PM   #140
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The prairie does have a 12' beam and weight out of the box,original specs is 12000#.

John
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