Prairie 29 engines

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Willow- Forgot to mention our wheel:banghead: which is 22DX16P.RH 3 blades
 
Al,
I doubt if the Marben is a FD boat. If it was you're cruising at a speed that I can just barely reach at WOT w a shorter boat. Should'nt be possible. I do however think the Marben is very close to FD and w the power at hand you would'nt want FD. You would'nt get close to a 7 knot cruise if it were.

I'm quite sure you showed us a pic of the Marben's stern. It's been quite awhile ago but my immage recollection says just a bit SD.

But you've got so much power it's possible. You're engine has well over double the displacement of mine. And a bit over twice the hp.

There is a Willard w an 80hp Cummins and the owner says he gets 8 knots. I assume that WOT and i've seen a pic of his boat underway w wake WAY bigger than anything Willy can muster.
 
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Eric,:flowers: it was included in the earlier post:

1978 Marben Flybridge Trawler Pilothouse Pocket Cruiser Title

Maybe it will not open.

With the 58 HP Perkins, we were able to obtain 6.5 at 2150 RPM same wheel as now. I don't care a hill of beans on F/D S/D, the damn boat will not plane if you put 1000HP into it!!! The best it will do with 85 HP is 7.5 at WOT, the stern sucks down so far that the boarding step is under water. With the 58 HP at WOT the near same result.

If it would help maybe TED would peek at the hull photos and settle it. I am comfortable with the boat no matter this tit for tat:).:thumb:
 
Yeah, that's one source I've heard of. If you get to know the distinctive paint color the reefer guys used, you can identify one of those surplus engines, even if it's been painted over - the base coat usually shows somewhere.

The Perkins was definitely used in the 26 foot motor whaleboats for a long time. Most Navy ships carried at least one and often more than one. I remember one dark & stormy night about 40 years ago when another vessel needed assistance...

Now-a-days there are tons of Isuzu, Mitsubishi and Kubota engines hitting the market from retired reefers. They would make great power plants for a modest size coastal cruiser.

I repowered my old Albin-25 with a new Isuzu 3CB industrial engine by adapting a seawater pump from a Yanmar and a heat exchanger/expansion tank from an Onan generator. I made a stainless sea water injection elbow in my shop and wired in some gauges. It made a great little unit, around 28 HP.

That boat would do 6.3 knots on 0.4 gph. I came from Portland, Maine to Dighton, Massachusetts, through the Cape Cod Canal and Narragansett Bay on 16 gallons of fuel.

Now I'm looking forward to more cruising adventures with a little more civilized comforts and better sea-keeping ability with the Prairie.

Cappy - have you cruised the Coast of Maine?

J.S.

What do you need to know about cruising in maine I lived up there 5 years while attending maine maritime academy
 
Our Prairie hull 50 has a 63hp Yanmar in it and it will push her with the bottom clean between 7 and 10kts depending on wind and current. Our prairie is loaded up more that a stock one as our interior is all solid teak and we have a 8kw gen 12 gallon water heater washer dryer and custom hardtop. The original owner who we are friends with told us the boat came with a mercruiser gas engine and it would run over 12kts then but would get squirley our yanmar pushes it nicely and sips fuel at about a gallon an hour but we get there in comfort.
 
Al,
Thanks for the pics and my memory was mostly correct. Bilges are a little softer than I had remembered but more importantly the transom is submerged about 8" and the run of the bottom is basically straight. Yes 200hp will plane this hull but at a high angle of attack due to the extremely soft chines.

salormike's boat and yours looks to be about perfectly powered for the hull. When you get a chance post the dia and pitch of the prop. If it's a 3 blade it can probably be optimized unless there's too much blade area. Even then one can cut down the blades and optimize the pitch.

I went back to you're link and from the pics it looks like there's prop clearence. However I assume w the little Perkins the prop is probably too much (big).
For your boat 22" dia is too much prop w the 2-1 gear. I'd cut it down as a knee jerk reaction. Going to a lower gear would be better but props are cheaper than gears. But w either the cut down prop or a different gear ratio you've got plenty of power

Yes I'd like to hear TAD's take on it too.
 
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Al,
Thanks for the pics and my memory was mostly correct. Bilges are a little softer than I had remembered but more importantly the transom is submerged about 8" and the run of the bottom is basically straight. Yes 200hp will plane this hull but at a high angle of attack due to the extremely soft chines.

salormike's boat and yours looks to be about perfectly powered for the hull. When you get a chance post the dia and pitch of the prop. If it's a 3 blade it can probably be optimized unless there's too much blade area. Even then one can cut down the blades and optimize the pitch.

I went back to you're link and from the pics it looks like there's prop clearence. However I assume w the little Perkins the prop is probably too much (big).

We got a new 3 bladed wheel that was spec and tuned to the boat we sent all the measurements to mfj and they sent us a prop we picked up over a kt with the new prop

ill get the numbers for you when i go down to the boat later.
 
Al,
Thanks for the pics and my memory was mostly correct. Bilges are a little softer than I had remembered but more importantly the transom is submerged about 8" and the run of the bottom is basically straight. Yes 200hp will plane this hull but at a high angle of attack due to the extremely soft chines.

salormike's boat and yours looks to be about perfectly powered for the hull. When you get a chance post the dia and pitch of the prop. If it's a 3 blade it can probably be optimized unless there's too much blade area. Even then one can cut down the blades and optimize the pitch.

I went back to you're link and from the pics it looks like there's prop clearence. However I assume w the little Perkins the prop is probably too much (big).
For your boat 22" dia is too much prop w the 2-1 gear. I'd cut it down as a knee jerk reaction. Going to a lower gear would be better but props are cheaper than gears. But w either the cut down prop or a different gear ratio you've got plenty of power

Yes I'd like to hear TAD's take on it too.


Eric, You consistently continue to miss the one important component we desired and acquired with this combination of the 4-236 with 2:1 gear retaining the original diameter/pitch wheel. QUITE!

We so enjoy the ability to reach hull speed at a very reasonable RPM.
We retain the working margin of 600 RPM between cruise and WOT assuring the engine is not being abused.

We do not have any intentions of changing any component of the running operation. Thanks for the suggestions. perhaps other forum members will utilize the information.:flowers:

Al-Ketchikan
 
Al I must have you confused w a Willow-B. And perhaps I've got a bit of Andrew w the steel boat mixed in. I'm out.
 
Al:

I too have a Prairie-29 with an engine that is way too large for the boat. Yours is a 4-cylinder, mine is a 6, and turbocharged to boot! ...talk about overkill.

As you do, I enjoy cruising about at a very low rpm, with attendant noise and fuel economy benefits. Yes, it has too much propeller to reach full rated rpm.

Who cares? (...not me)

I suppose it means I won't have to add ballast, the 6-354T being such a gawd-amighty lump of cast iron. Made when men were men and engines were cast iron.

It wouldn't have been my first choice of engine, but it's bought and paid for, installed & running so I'm going to go with it.

So far, I've found it needs a new sea water pump, exhaust elbow, thermostats, hoses and a complete service, the filters not having been changed since 2011.

The hour meter wasn't working when I got the boat, but it shows ~1200 hours. Visual clues lead me to think this engine was a takeout from another boat and swapped into Rise 'n Shine. Maybe by the same guy who removed the flying bridge? Anyway, it shows signs of having many more hours than what shows on the meter.

I don't have nearly enough sea time to comment about the boat's handling. That's for next year, after the engine gets some love.

Looking forward to warm weather!

J.S.
 
Sailormike
I'm not so much looking for information as looking for folks who are interested in setting up cruises. Are you still in the area, perhaps?

Cheers!

J.S.
 
Sailormike
I'm not so much looking for information as looking for folks who are interested in setting up cruises. Are you still in the area, perhaps?

Cheers!

J.S.

No thank goodness but i know a fair amount about the area i have moved back down south now
 
Willow- We have a 27 foot Marben trawler which has a 10 foot beam at the widest point although the stern tapers to 9 foot beam across the deck. We draw 3 feet and consider our hull F/D (Eric-:nonono:) As I review your post I agree to the 'Hobby Horse' into head seas. We recently pulled a Perkins 4-154 (58 HP) out and installed a running Perkins 4-236 in its place.(85HP)
The 154 had a 3;1 and we changed to a 2;1 with the 236 and kept the same wheel. We are honorably over wheeled by forum standards. Our top RPM is 2000 on a 2800 rated RPM scale. Now Willow, we should have a lower hull speed than you yet when we use the Vicprop formula

:Vicprop - Propeller Calculator

we have and do cruise, at the hull speed of 6.9 knots the formula produces. We run at 1400 RPM so we still have a safe margin of 600 RPM which as you indicate, is the best setting as anymore throttle just creates water displacement, noise, and smoke, very little improvement in speed. We consume 1.3 gallons per hour. We think we are fine with this over wheel results.
Okay- Now here is an area to compare. We have a limited fuel capacity of 90 gallons, 48 gallons of water. The engine/gear weight is 1500#. We have little in the area of anchor chain, 25 feet, so that is not a factor by itself.
Due to the "Hobby Horse" effect combined with a horrid snap roll in the for mentioned weight factors, we were alarmed at the motion of the boat, unsafe not but very uncomfortable would be fair.
As a result of many suggestions from our Forum members, all in good intent and welcome, we were fortunate to local locally, 50# lead ingots. We purchased in total 1300# and installed them thus, We added one 50# directly to the chain locker floor. At the junction of the v-berth there is a floor locker cabin, we added one 50# to the floor of that locker. Moving back we installed
6- 50# ingots above the keel in a existing alley. Under the engine/gear we placed 4-50# ingots. Along side the engine bed-port side, we placed 6-50# ingots favoring aft abeam the reduction gear. We placed 4-50# ingots on the Starboard side mid ship of the engine (Aft of this weight is located the 11 gallon hot water tank which offsets. The remaining ingots were placed in the lazeret evenly aside the rudder stock.
The outcome is a perfectly balanced boat!!! We cut the Hobby Horse down to nil, the boat cuts more than lifts. Following seas affect us sitll yet at a lessor degree, the yawl is slowed way down. We can ride beam seas in a fashion where the boat rides up, the wave or swell moves UNDER, the boat remains in a vertical stance, any roll is gentle and slow.
All of this weight on top of the as built of 1500# of lead in the keel, and the boat burns not enough additional fuel to make a noticeable difference.

Here is a site of a sister boat that we almost purchased:


1978 Marben Flybridge Trawler Pilothouse Pocket Cruiser Title

Would you be kind enough to view the photos and comment as to how close all of this is to your boat/conditions? Note the fuel and such in this boat and understand the weight difference between our boat and this one due to tankage alone.

Long response, sorry:angel::angel:

Al-Ketchikan


Thank you all for the info.

I do like the Marben!!! The Prairie is similar. The hulls seem to be similar as well, except the harder chine on the Prairie vs rounded on the Marben. As stated, the Marben hull tapers aft. This makes for a more efficient design. Both hull shapes can be 'called' SD if it pleases some, but it's gonna take more power than the little engine rooms can hold to push these hulls 'on top'! It is my belief that these vessels were designed as 7-knot boats.

By the read, you have accomplished what few have attempted. A BALANCED BOAT. Well done!

Your re-power info and link to the Prop Calculator confirms my own thoughts of adding pitch.
I have been quite occupied with business over the months since leaving Willow B in Waukegan, IL last summer. Now that things have slowed down, I've had time to reflect. I am currently pitched light. I now believe too light. While hauled, I plan to add pitch. I feel this will buy me what I am seeking.

I am not looking for much, just wish to run as efficient as possible. It's not even a $$$ thing. Just wish to be efficient in all I do.

The 4-108 is currently operating at 2500-2600 rpm consuming fuel at a rate of 1 gal/hr, which is expected. However, I believe I can get 20% more distance traveled in that same hour.
 
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Willow-B,
I don't think it matters if you're at 2700 or 1400rpm. The little Perky will still burn about exactly 1gph. And that's what it takes to push our boats. I run 2300 and burn 1gph.
 
I agree wholeheartedly, but I'd like to break 6-knots doing it. I don't want to overdrive the hull, or push up on the bow wave, or any such impossible nonsense. I do understand low horsepower, fluid dynamics and such. I am just looking to efficiently push to theoretical hull speed. With a 26' LWL, I should easily be over 6.5k. The engine is VERY lightly loaded. I just don't wish to run a 35-36 year old engine over 2500-2600 rpm.


As I am already swinging an18" wheel, the next step is to throw a bit more of pitch at it... The worse that can happen is that I load the engine by 20%, which I feel is available and unused.

I use the same philosophy with Class 8 trucks. I purchase used with the final gear 'close' to what I want. Then fine tune with tires. I end up with a truck that gives me the pulling power and cruise I desire at a fraction 1/5 of purchasing new.
 
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Willow-B,
I see you've got a 1.9-1 gear. You probably have a very low pitch.

I like to prop my engine to turn rated rpm at WOT .. give or take 50rpm. That's 3000 for your engine and mine. Consider that I have an 18X13 prop. That would suggest your optimum prop could be a 16"X10" or there abouts. Maybe a 16X13 or 14 would be good. Have you run it through a prop calculator like VIC ____? With less than 2-1 i'm think'in you have much too big of a prop. With my Albin 25 I had a 34hp Yanmar and a 15 or 16" dia. And a 1.14-1 gear. Maybe David will come along w his prop calculator.

All stock Willard 30' boats came w a 2.57-1 gear and an 18"X14" pitch prop. And they were overpropped ... could only make 2750rpm. One inch less pitch brought mine up to 3000rpm. By the way the Willard makes 6.15 knots at 2300rpm and 6.4 at 2500. Being a FD hull the Willard is overdriven (the hull) at 6.5 knots+.
 
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Yeah, I believed I lied to you. I have a BW 2.9 gear. Not a 1.9 as earlier stated. The 50 hp Prairies originally carried a 18 X 12 wheel. I failed to see any entry in the Maint Log indicating re-pitching the prop. The prop calculators suggest I pitch to 14" which is up 2".

I don't mind loading the engine, as long as I don't overload.
 
OK good,
The Perkies are not 50hp though unless they are in an English taxi cab. They are:
50hp @ 4000rpm
42hp (I think) @ 3600rpm
And
36hp @ 3000rpm
Overpropping 250rpm (to 2750rpm) will loose aboyt 3hp. I really don't know if the engine ratings over 3000rpm involved mechanically different engines like different timing or bigger injectors.

With your 2.9-1 gear you probably could use a 19 or maybe a 20" prop.
The 18X12 prop would definitely be underpropped ... better than overpropped IMO but not right .. or correct.
Again I'd like to see what a prop calculator would come up with.

Also I wouldn't worry about running the old Perky at 2700rpm .. or so when they have been rated for much higher engine speeds than that.
 
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I just don't like the vibration above 25-2600. I have a connection to a prop shop that work with shrimp boats down in south La. Was told to give 'em a call after the first and they can tell me what I need. Was also told by an old prop man how to prop shrimp boat correctly, but boat needs to be in the water. WOT, note rpm. Tie fast to dock, WOT, note rpm. If within 250 or so, correctly propped. Again, this is for a shrimp boat that's pulling/pushing nets.

I do have a 4-blade of unknown size as a spare. I saw it in the lazarette last year.

I was looking at pics earlier and I believe I have room for a 20" wheel.

All advice and comments are welcome and appreciated.
 
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Okay... Just got off phone with Toups Prop Svs in Abbeyville, La.

After researching boat & 4-108 they advised that I am extremely under propped. Suggested ideally to move up to 20" wheel. But advised that as I already own both a 3 & 4 blade 18" wheels, simply repitch the 4-Blade to 14" of pitch or the 3-blade to 15" of pitch and you are where you need to be. Said as I'm not trying to push any harder than hull speed, should not be much additional load on engine. As long I'm not black smoking, I should see the results I'm looking for at 25-2600 rpm. Stated he has experience with 'those little Perkins' and 25-26 is the sweet spot.

Thanks to all.
 
Willow,
I'm propped at rated rpm of 3000 and run at 2300. When I run up to 2500 there is considerably more noise and a bit more vib too. 22-2300 seems the sweet spot.
The prop guy was a good find.
 
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Willow,
I'm propped at rated rpm of 3000 and run at 2300. When I run up to 2500 there is considerably more noise and a bit more vib too. 22-2300 seems the sweet spot.
The prop guy was a good find.


We are speaking the same language. Maybe just a different dialect.

Example:
I am propped at 3300 WOT and 2500 is MY sweet spot. 2500 is 75%
You are propped at 3000 and 2300 is YOUR sweet spot. 2300 is 76%

By the time Willow B is splashed in late May, she will be sporting a shiny reworked 18 X 14 4-Blade prop. We will see where my WOT ends up and I will cruise at 75% (her new sweet spot)

I agree, the prop guy was a good find. An old friend who's a retired shrimp boat captain (Clay) called me yesterday with his info and told me to trust him. I will post results as they happen

If traveling the West Gulf ICW in SW La, Clay is the lock master of the Calcasieu Lock.

Thanks Eric
 
Okay... Just got off phone with Toups Prop Svs in Abbeyville, La.

After researching boat & 4-108 they advised that I am extremely under propped. Suggested ideally to move up to 20" wheel. But advised that as I already own both a 3 & 4 blade 18" wheels, simply repitch the 4-Blade to 14" of pitch or the 3-blade to 15" of pitch and you are where you need to be. Said as I'm not trying to push any harder than hull speed, should not be much additional load on engine. As long I'm not black smoking, I should see the results I'm looking for at 25-2600 rpm. Stated he has experience with 'those little Perkins' and 25-26 is the sweet spot.

Thanks to all.
Small world-I've done business with Toup's since 1971-know their stuff-FYI I have a '83 30' Atlantic (updated Prairie 29) with a 165 Volvo swinging a 18 dia 15 pitch 4 blade-WOT 2800 (over propped, I know) but reach hull speed at 16 to 1800 rpm-7 knts-very smooth and quite-less than 2 gals per hour.
 
Small world-I've done business with Toup's since 1971-know their stuff-FYI I have a '83 30' Atlantic (updated Prairie 29) with a 165 Volvo swinging a 18 dia 15 pitch 4 blade-WOT 2800 (over propped, I know) but reach hull speed at 16 to 1800 rpm-7 knts-very smooth and quite-less than 2 gals per hour.


It is a small world, indeed... I was born & raised in Lake Charles. I started my first trucking company in Lafayette in1981. Lived thru the early 1980's oilfield collapse.

I love the Prairie/Atlantic platform. I am hoping to reach hull speed without increasing rpm. Maybe doable, maybe not, with such a small powerplant. We will install the 4-blade wheel and see what we have. Plans are already in place for La-Tx coastal cruise in 2017.
 
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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?
 
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
 
Willow-B wrote;
"We are speaking the same language. Maybe just a different dialect.
Example:
I am propped at 3300 WOT and 2500 is MY sweet spot. 2500 is 75%
You are propped at 3000 and 2300 is YOUR sweet spot. 2300 is 76%"

For your information my 2300 and apparent 2500rpm is 50% load. You are 300 rpm over me. I think you'll like 2300. That gives you less than 20hp available at that rpm so don't overdo the pitch increase. One inch should do it IMO. W my Perky I went from 2750rpm WOT to 3000rpm w a 1" reduction in pitch. A 1" pitch increase should ......
I just remembered you have the 2.9-1 gear. I'll leave the above FYI.
 
I didn't mean you were @ 75% load. You are at 75% rpm, which is where a diesel should run.
 
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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.
 

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