How much HP?

I've had Prairie 29's on my short list for awhile now. I'd appreciate any comments on how much horsepower is needed to make sure a 29 can handle running against strong tides, currents, head winds and/or head seas. I've seen 29's with 50HP, 85HP and 100HP. What's needed in the real world?

Let's see a good pic of the hull aft.

manyboats said:

Let's see a good pic of the hull aft.

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Eric,

At one time, I was looking at the P29 too. Here are some pics. An interesting construction note is that Hargrave designed this boat with generous beam above the waterline, but kept the BWL as narrow as possible. Note the tapered/softer chine at the transom. I read this was to reduce wetted surface and make the boat more economical to operate. It also supposedly made rolling less harsh than if the beam had been carried all the way to the waterline with a hard chine.

you don't need extra power to fight tides and currents because the boat will only go so fast through the water unless it planes. It does not matter how fast the water is moving. Waves and wind age are a different matter and extra HP helps a lot especially in bucking tall head seas that tend to stall the boat.
It is not the size of the engine that determines how much fuel you use but the speed you try to run. At 5 knots all engines will probably use similar fuel so I would go for the larger engine to have reserve power all things being equal which they never are.

bayview said:

you don't need extra power to fight tides and currents because the boat will only go so fast through the water unless it planes. It does not matter how fast the water is moving. Waves and wind age are a different matter and extra HP helps a lot especially in bucking tall head seas that tend to stall the boat.
It is not the size of the engine that determines how much fuel you use but the speed you try to run. At 5 knots all engines will probably use similar fuel so I would go for the larger engine to have reserve power all things being equal which they never are.

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Anyone have direct experience with a Prairie 29?

TF Member FLAGOLD has extensive experience with Prairie 29. His name is Matt Mattson and has a lot of videos on youtube about cruising his boat.

Boy does that bottom look like a Hatteras

Wonder why, by the size of that prop that boat isn't a powerhouse.

No personal experience with Prairie 29s, but lots of experience with displacement hulls in that size and those HP engines. I am guessing that the 50 HP motor is probably a Perkins 4-108. It is called a 50 HP but it makes that at a high RPM that you would never run at. The 85HP would be a Perkins 4-236. Now you are talking! Lots of grunt at 1500-1800 RPM! It will push that boat as fast as it will ever go! This is the motor I would choose.

I own a Prairie 29,SUE MARIE, with a Perkins 4-108,50HP. She has a left hand turning 18x12 driven thru a BW 2'9. Engine is listed at a 4000 rpm, real number is more like 3600. Sue Marie, cruises at 6.3+/_ at 2700 rpm. At 3000rpm she will reach 7. I have run one with the 4-236, an 85hp engine. The top there is 2800rpm. That would be my preference if I were building new.

I have no real complaints with the 4-108. She averages 1gal per hour and runs strong.

John

Scary said:

Wonder why, by the size of that prop that boat isn't a powerhouse.

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Didn't Hargrave design the older Hatteras motor yacht hulls?

Thanks Larry for the pics.

All the engines mentioned would be appropriate .... probably.
This is at least a mid speed SD hull. But her wide beam may cause her to plow along bow high in the vicinity of "hump speed" making her hard to power intelligently. Running semi-slow (8 to 14 knots or so) is best done w a longer narrower boat.
But she would definitely benefit from more power than a similar length full displacement (FD) boat like my Willard .... that requires less than 35hp total and 18 for cruising.

35hp would be insufficient power for the Prairie. Fifty hp would be about right if one was not interested in top speeds over 7 knots. You may get 8 or 9 knots ......... I'm not sure ..with 85hp. Ask Prairie owners. But I would go w 50hp. And as mentioned the 107 and 108 cu in Perkins engines are only 36hp at 3000rpm. A 55hp Yanmar JH NA engine would be excellent as would be a 54hp Isuzu ... one of my favorites. An 80hp 4 cyl Lehman would also be an obvious candidate. Any good fifty to sixty hp engine should work out fine. You may come across a 75 or so hp Nissan engine. They were found in 27' Albins for one example. The Nissan is a 6cyl engine.

I think Al in Ketchikan has a Prarie. Contact him.

If you look at the stern, the stern quarter and the entry you think you are looking at the old Hatteras 34

Capt.Bill11 said:

Didn't Hargrave design the older Hatteras motor yacht hulls?

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Yes he did. The Prairie 29 has sometimes been referred to as a 'Baby Hatteras' because of its lineage.

In the 70's I studied yacht design at Westlawn, and actually still have drawings I submitted that were graded by JBH, Jack B. Hargrave. He was on staff in those years, I think maybe as a volunteer to get Westlawn off the ground. He even liked one of my designs!


Larry
M/V Boomarang

Yes

Capt.Bill11 said:

Didn't Hargrave design the older Hatteras motor yacht hulls?

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Yes and I think he new what he was doing.

Sortie,
What does your Prairie weigh?

Larry M,
I was hot to go to Westlawn a long time ago, probably in the 60s. Was look'in at Embry Riddle fly boy school too.
In the middle picture in your post #3 notice the chine is not straight as many/most boats are. Generally speaking unless it's a planing hull straight lines fore and aft are undesirable. Sides and bottom included. Landlubbers mostly don't see the difference but Hargrave was no landlubber.
Something odd about that boat in the ctr pic is that it looks like the hole in the rudder dosn't even come close to lining up w the P shaft.

Eric, 1300; you are correct, the hole in the rudder does not line up with the shaft. We had to drop the rudder to get the shaft out.

John

These posts are very informative. I looked at some of Flagold's excellent videos.
I believe his boat had been repowered with a 6-cyl Yanmar. I assume that motor would be rated higher than 50HP.

Thank you for all these responses.

I was under the impression that Mischief was repowered with Yanmar 55. The Perkins 85 gives you more power at a lesser rpm, top end slightly higher. This hull is going to cruise between 6-7 knts regardless of power. Too big of an engine could in fact be counter productive.

Check the postings on Miss Dot Dee. He saw a dramatic improvement in performance when he stripped his layers of bottom paint.

I am content with the performance of our boat. It is quiet, efficient and gives us all the speed we need for now. These vessels were not designed to be speed boats. .

I agree with Eric, I love the Isuzu engine. If I needed a new engine it would be my first choice, then the Yanmar 55. The Perkins 4236 is also a good engine.

Good Luck.
John

I stand corrected on the repower on Flagold's Mischief:

". . . New Yanmar 4JHE installed 2008 - 436 hours."

Eric- "Al in Ketchikan" here. We own a Marben 27 foot. Here is a copy of a sister advertisement. You can select the bottom to see that it is completely different from the Prairie. Al

1978 Marben Flybridge Trawler Pilothouse Pocket Cruiser Title

By the way- We have a Perkins 4-154. this one above has the Perkins 4-236 which I now state is the better choice and one that I am pursuing. Stuggling at under or near 6 knts at 2300 RPM on a 3000 RPM rated engine with a three to one reduction, has become a issue. The hull works out to 7 knots by numbers. The Perkins 4-236 will provide that at 1600-1800 with a two to one reduction and allow the extra kick against head seas when needed.
Al.

Al so sorry I got the boats confused.

The 154 should be plenty of power for your Marben. What's your prop dia? Three to one looks like a very deep reduction. Willy is 2.57-1 w an 18" X 14 prop. We have a 3000rpm engine and run 2300 at 6.15 knots cruising .. One gph. A 3-1 reduction should beg for a 20" prop.

Thread creep!
22X16 LH
Al

I would respectfully suggest you run your boat details through Vicprop and the specsheet will give you the correct horsepower and prop, the engine make is matter of owners choice and the depth of his pocket.
I run Perkins 4236 in both my boats simply because they are damn near indestructible and will probably still be around when I'm gone to Fiddlers Green.

Irish,
I think the Perkins 236 was standard in the Willard 36.

I started w the 107 in Willy but it was hard starting and didn't like the idea of having a hard starting engine in Alaska. Are the bigger Perkins reasonably smooth? They say the Lehman 4cyl is'nt smooth. And does the 154 and 236 have prechambers or is it direct. Seems to me the prechambers were a new thing in the early 60s. I remember working in a powerhouse in Alaska and reading a magazine article about the English Perkins w the pre combustion chambers and the injectors within. Perkins must have quite a history.

Why weren't the Perkins engines employed in boats like the GB36. I think they just wanted to offer a slow boat and a faster boat. And they did it (unfortunately) w one hull that was optimized for only faster.

Irish Rambler,
That and parts for 4-236 seemingly are laying around like that of the old 671 Jimmys in every backyard!!! Finding parts for the 4-154 is like finding the remains of a DoDo bird! If I find the 4-236 replacement is fiscally doable from an installation point I will be joining you with same in our boat as I have access to a recent marine gen set replacement requiring only those items needed to take it from a gen set to a drive engine . I like the 1600-1800 RPM rhythm knowing too that there is spare "Umph" to fight the tide/wind when thought required.
According to Vicprop our current wheel is right on. Over propping is not a consideration.
Were I to have the opportunity to own a 29 foot Prairie and had the chance to choose an engine it would start with the 4-236 nothing smaller.
In my searching I have found a rebuilt 4-236 by a known builder (TAD?) is a fiscal consideration when judged against a brand new engine .
That and confirmation of what you have discovered with actual ownership. Nothing against the newer engine offerings, only a personal opinion.

Al

Eric-
Having just purchased a backup 4-154 as my "Belt and Suspender" policy a bit of research was undertaken. I purchased a supposed lightly used (300 hrs) W58 which is built on the Perkins 4-154 block. Westerbeke had access to the Perkins between the years 1980 and 1991. The head has the pre-heaters where as the original Perkins did not. The original 4-154 employed external preheat or the use of "Panther Piss" (Start fluid) in moderation by a predetermined injection system. I do not have that on our 4-154. It is either start fluid (which I dislike using) or a longer process of preheat with a external hot water unit. It works however requires a trip down to the boat prior or an early start to allow for the preheat.
The Perkins 4-236 that I have access to is somewhere around 25-30 years old and has been maintained with schedule, no doubt a good candidate for a rebuild and installation finding that it will be a fiscal fit. (Yes! in spite of having a backup to the 4-154!)
The engines both, 4-154 and 4-236 are quite smooth running more so than as you stated and I have heard, the four cyl. Ford.
Note we all are speaking to the natural aspirated engines in this discussion. Trust the Prairie owner is obtaining information he can use.
Regards.
Al

Al:

Have you ever tried spinning the engine with fuel off to pre heat the combustion chamber before fueling?
Vet

Irish Rambler said:

I run Perkins 4236 in both my boats simply because they are damn near indestructible and will probably still be around when I'm gone to Fiddlers Green.

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Bringing my boat from the East coast of Florida (in 2012) to the North gulf coast where it is now, I got the raw water intake for the port engine stopped up (big fish kill off St. Pete, and it was sucking them up against the intake), was stupidly not watching the temperature gauge, and the engine badly overheated. When I say badly, I mean the temp gauge pegged, all the paint burnt off the engine, and the soot from the exhaust (raw water hose came off) finally stopped up the air intake so that the revs dropped and I noticed it and shut it off. I limped into Clearwater on the starboard engine and called Marine Doctor. I had visions of a ruined engine, but he just laughed and said that it would take more than that to kill a Perkins 4-236. Sure enough, he had it up and running in a few hours, and it has run flawlessly ever since. So I am sold on the engine!

more power

Bayview-

Good catch on your part for the method.

The boat was constructed in 1978 yet the SN: of the Perkins indicated being built before 1966!.

Yep, To create internal heat within the cylinders. Turn it over for 10-15 seconds, stop wait, turn it over for another short period, stop- Third attempt will sometimes do the trick, yet, with a 50 year old engine and untold recorded engine hours other than on the current reading, I suspect a bit tired!! No smoke, and good oil pressure. ( There is a noticeable bit of "Blow-by)

The external heater is acceptable, sort of gives the aspect of having an old heavy duty Atlas procedure and part of the not too distant nautical world. Besides, the coffee is on the boil by the time the starting process begins!

Al