Prairie 29 engines

Well damn!!! I have never heard of a P29 with a 6354!!! How fast does it go at WOT???? It should plane since it is a semi planing hull. I do know when Atlantic took over they did do boats with twin 115hp Volvos on the same hull. I would not envy that engine space. Anyway, has the boat had extensive interior additions or customizations??? The only reason I ask is that there was one down here with the fly bridge off of it that had an "eccentric" interior. It was actually pretty well done but very different!

And quieter than a CUmmins????...NO WAY!!!!....

Yes, I think the interior was re-done. The galley is up to port, and there's a small stateroom below, just forward of the helm, with a bunk that only measures 5'-9" long.

Does this sound like the boat you saw?

As far as Cummins engines go, I'm a HUGE fan of them for all purposes other than boats. That's just because they're too damn loud, at least the older 12-valve ones. The newer 24-valve ones are a completely different ball game. Cummins company is an American success story, competing with all the other manufacturers all over the world and winning because their machines are dependable, economical and durable, and they have good customer support. Who said Americans can't build stuff?

...but the 12-valve B-series make too much noise for my taste. YMMV, of course.

Driftless said:

Yes, I think the interior was re-done. The galley is up to port, and there's a small stateroom below, just forward of the helm, with a bunk that only measures 5'-9" long.

Does this sound like the boat you saw?

As far as Cummins engines go, I'm a HUGE fan of them for all purposes other than boats. That's just because they're too damn loud, at least the older 12-valve ones. The newer 24-valve ones are a completely different ball game. Cummins company is an American success story, competing with all the other manufacturers all over the world and winning because their machines are dependable, economical and durable, and they have good customer support. Who said Americans can't build stuff?

...but the 12-valve B-series make too much noise for my taste. YMMV, of course.

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That is a standard layout. The one I was referring to had a teak headliner and also had a diesel heater in the fore peak that was surrounded by a tile semi enclosure.

And I was just messing with you on the Cummins. Mine are pretty damn quiet though. So much so that I have a hard time hearing them to sync them.

My 30' 8 ton trawler only burns 1 GPH instead of 4. I would guess you're fuel burn should be 1.5 to 1.8 gph .... taking into consideration that it's a SD hull not FD. My Willard originally had the 107/108 Perkins engine and the replacement I chose is exactly the same size .. even the same bore and stroke. A new Japanese engine v/s an old British engine. Both burn almost exactly the same fuel though.

manyboats said:

My 30' 8 ton trawler only burns 1 GPH instead of 4. I would guess you're fuel burn should be 1.5 to 1.8 gph .... taking into consideration that it's a SD hull not FD. My Willard originally had the 107/108 Perkins engine and the replacement I chose is exactly the same size .. even the same bore and stroke. A new Japanese engine v/s an old British engine. Both burn almost exactly the same fuel though.

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My 9500 lb. Cape dory with a 200 hp Volvo burns <2 GPH at a 7 knot cruise...
SD hull... Will max out at 16 knots at WOT but rarely if ever sees that speed..

The Cummins 12v B motor is loud. And the surprising reason is: Timing gears!!! They have a bad case of lash rattle that is louder than combustion noise. Same with the C motor, like I own. Open the oil fill cap on the timing gear housing and it sounds like it is grinding gravel!! Just noise though, does not harm anything. The 24v Q series took care of this. QQQQQuiet.

Not sure how Perkins did it, but that 354 at low revs is also quiet. No, or very little lash rattle. I love the sound of those old beasts.

Heron said:

My 9500 lb. Cape dory with a 200 hp Volvo burns <2 GPH at a 7 knot cruise...
SD hull... Will max out at 16 knots at WOT but rarely if ever sees that speed..

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Yes that's about what I would expect. I think a GB or a NT 32 would run 7 knots on 2 gph.

My guess is that I'll use ~ 2gph @ 7-1/2 knots using 1400 rpm. One disadvantage of that much-larger-than-needed engine is that at low power it's using a disproportionate quantity of fuel just keeping itself turning rather than moving the boat.

A friends Marine Trader 40 uses 1.8 gph at 7 knots with his Isuzu 120 (4BG1-T) which I sold him six years ago. One upside is that in the cabin it's uber-quiet and from the flying bridge it's silent. It's like being propelled by an electric motor. I don't know what that boat weighs, but it's a lot.

OTOH, another friend's 32' Trojan used 23 gallons going 12 miles down & back the Taunton River to the battleship on his twin 454 Chevy's. That's why it spends most of the summer at the dock.

Onward!

J.S.

My Prairie 29' (hull # 6) has a 4-108. That engine is a 3600rpm max engine. She does 6.3 at 2550RPM. Burns about 1 gal per hour. She is quiet and smooth at that rpm, thus that's where she runs. The boat only has had two owners, never had the bottom stripped, got a lot of paint. hanging on. Gear is a 2.91 Velvet drive LH, prop is a 18x12 three blade. No problem getting parts, easy to work on.


John

Sortie,
The Perkins 4-108 is a 3000rpm engine in any boat application I've heard of. It's Frequiently found overpropped in original condition w older boats. My 4-107 (same engine except it has removable liners) was originally equiped w an 18x14 prop. WOT at 2750. I took out an inch of pitch and it ran 3000 at WOT. The Perkins is 36hp at 3000rpm, 40hp at 3600rpm and 50 at 4000. I really don't know if they change the maximum amount of fuel or what for the three different ratings.

My present engine is an S4L2 Mitsubishi. Same bore and stroke as the Perkins .. 78X92. Close to the same engine.
My gear is 2.57-1 and it burns about 1gph. I cruise at 6.15 knots almost always and occasionally 2500.

@ Driftless: I'll be keeping an eye out for ya next summer at Cuttyhunk.

Cappy:

Yeah, that's a nice destination for me as well.

J.S.

Sortie,
My post (#40) was confusing re the last paragraph. I usually run Willy at 2300rpm for the 6.15 knots and occasionally at 2500 for about 6.4 knots.

Since you have a considerably lower gear ratio and less pitch on the 18" prop (same as me) you're quite underpropped .. and that's unusual on this forum. I'll bet the engine runs real sweet w the higher rpm and light load your combination provides. And as I recall that's essentially what you said. It's a good set up you've got and you'll never overload her. Since some Perkins 107/108 engines run to 4000rpm I doubt you'll over rev her either. The 4000rpm engines were (as I recall reading) English taxi cab engines .. the 50hp versions.

Since you are happy w it I'd say just run her as is. You're fuel consumption hasn't suffered at all as it's the same as mine.

@driftless: How fast would she go hooked up? Wondering if that extra HP does any appreciable difference to speed. Or was 8.4 the top speed?

Cappy:

My sense is that the extra potential horsepower doesn't really make any useful increase in speed for two reasons: First, the larger-than-ideal propeller keeps the engine from making full rated power and second, the hull "squats" in the water and doesn't have any inclination to plane. I brought 'er up from Mystic at 8-point-something knots and 4-point-something gallons per hour, and my sense is that it's steeply up hill from there.

However, I haven't fully explored the behavior and won't really know until next season. Right now Rise 'n Shine is hauled for the winter and there are loads of little projects to tend to.

With this big an engine in a Prairie-29, the engine is stuffed tight up against the floor, so I have to dive under the floorboards to get at the secondary fuel filter and sea water pump. (Oh boy...)

But, it's a big, heavy boat that cuts through the chop (like the afternoon slop out of the southwest on Buzzards Bay) much better than the Albin-25.

Color me happy...

J.S.

There is quite a lot of info (mostly anecdotal) on this forum which sort of confirms what you state.

I have the 4.236 engine. This is a 2800 rpm engine.

I know that when I plod along at 6.1 to 6.3 knots 2000 rpm I burn slightly less than a gallon an hour. But when I push it to 2800 I make it to 7.2 or so but it burns 5 gph. It's amazing how the little increase in speed sucks the fuel down. Hull speed is a brick wall. I don't usually go to 2800 though, I don't see any need to beat a 20 (since rebuild) yr old engine. (That's actually 34yrs old).

I have run for 30 hours this summer at 2000 and burned 30 gallons. So I am confident in the gph figures at 2000. But have not run enough at 2800 to be confident in accurate figures. The upper end speed doesn't warrant the higher fuel consumption in my mind. I didn't buy a speed boat, I bought a trawler.

You're right about the SW chop.

Perkins 4-154 is the engine with more parts challenges. That and the rear seal leaking issue which is a 'If not now, when but it will' situation. I am not sure if this is an issue on the 4-107 or the 108.
The 4-236 seems the most favorable four cylinder Perkins in the older series.
It was the choice when I replaced the 4-154.
Al-Ketchikan

Most Willard's have Perkins engines.
The 107/108 in the W30's
The 236 in the W36
And I think the W40's often have 6-354 (or whatever).

Cappy you've got a real fuel sipper. My engine is half the size but burns about the same. How did you arrive at your WOT fuel burn of 5gph? Sounds about right though.

I burn from one side or the other. I have 'tank tender' gauges. I religiously check before and after Levels on trips.

This is also how I know how much a Perkins 4.236 returns from pumping from one tank and returning to another and seeing the difference.

The difference in fuel consumption is apparent even after a two hour trip at higher Rpms. But I hate to run her up that hard.

I have the 4 108. The boat was sold in Jan. 1978,hull number 7. I bought her from the original owner in 2010. Have all the original paper work including manual's for both boat and engine. The 4 108 is described as a 4000rpm engine, but is qualified by the builder as being a 3600rpm engine. With the present (also original specs.) 2.9;1 gear, and 18x12 L H prop(3 blade) she will turn up to 3500, providing a 7.8 speed. However, she quickly starts to overheat. My mechanic tells me this is common for the 4 108 at that rpm. Needles to say, we don't do that.


PO told me that the boat when new, cruised at 7 at 2600, and did 8 at 2900/3000. He claimed the fuel consumption rose dramatically at that rpm. Not a surprise. If I needed a new engine I would consider the 4 236. However, I do not. Very content with my fuel economy and speed and she is very comfortable, noise and ride. Sounds lie a sewing machine. No problems, she runs well, she likes it, thus I like it.


John

Sortie:

It's interesting to hear your experience with the 4-108. They're quite a good little engine. There was a guy near here who bought a boatload of them when they were surplus from truck refrigeration units and sold them as "rebuilt". Most of them were simply test run, steam cleaned and painted.

But, they're good enough engines that even after thousands of hours, most of them still ran fine.

They only have three main bearings which is considered an anachronism today, but who cares? They run fine and that's all that matters - uber-dependable. The only complaint I've heard about them is they tend to leak oil more than a contemporary Japanese engine. So, I say - wipe up occasionally, then pop a tab and relax.

It does make my turbocharged 6-354 seem like ridiculous overkill...

Onward!

J.S.

Interesting post as usual



Had a potential buyer of my boat on-board Sunday who once owned the same boat as mine 10 years ago that had a 4 cylinder Perkins around 500kg

His first comments were how stable my boat felt to his and put it down to Perkins 6 I have in mine he also commented how much quieter mine is

When he saw we were doing 1200 rpm at 6.8 knots he said he would have need to be doing 2200 for the same speed .

So interesting the big heavy motors may have been fitted for a purpose other than HP ?

The truck, " Thermo king " engines can be bought for short money,according to FF as little as $300. I haven't confirmed this because I don't have a need for that engine. There is a thermo king facility near my house but have never stopped in to check o availability or price. If its true these would be a great engine to have in a boat. Lots of the old navy 26' whaleboats had these engines.

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.

I don't think the Prarie has better sea keeping abilities than the Albin or that the Albin is better in that regard. Not knock'in either boat.

I had an Albin w a 3cyl Yanmar for 6 years before my present Willard and often wish I had my Albin back again. Be careful what you wish for as they say and two foot itis will eventially lead you astray. Who knows exactly where that point is. Seems everybody does.

No Maine Cruising (on a Trawler). But have gone from Cape Cod Canal to Boston, Salem, Gloucester, Portsmouth, Portland, Searsport and Bucksport by Tug.

I have done Buzzards Bay, Islands, Cape, Canal, Plymouth, Scituate, Hull, Salem, Gloucester, Anisquam and Rockport though. Next summers trip is P Town. Maybe Nantucket. Have to get a Jetski to keep the wives speed demon satisfied. Never thought I would have to have a 'fast toy' to keep the natives happy!

manyboats said:

I don't think the Prarie has better sea keeping abilities than the Albin or that the Albin is better in that regard.

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I'm not sure either. The prairie is really sharp and snappy in a beam sea. I do almost as much 'tacking' in the prairie on a lumpy day as I did on a Ranger 30.

Cappy208,
If you've had an Albin 25 you know all about "snap roll".

Cappy:

That Provincetown idea has merit... I definitely want to go along, though it all depends on work schedule for myself and the Commodore. Her schedule opens up in late June when school lets out.

J.S.

Manyboats:

Are you comparing the sea-keeping of an Albin-25 to the Prairie-29? All I can say is that from my experience, the ride of the Prairie in head or beam seas is much more gentle that the Albin, mainly I think due to the much heavier displacement. But I don't have any actual design data only my "seat of the pants" experience.

The A-25 is a magnificent little vessel, and I had a ton of fun on 'er, always in complete safety. But it did get uncomfortable, such as in the westbound trip from the Cape Cod Canal to the mouth of the Sakonnet River in late afternoon. THAT amounted to four plus hours in a washing machine.

I decided then and there that the next time I took Driftless to Maine it was going to be on I-95 rather than via the Cape Cod Canal. One of the advantages of that boat was the ability to trailer it easily, which clearly the Prairie cannot.

BTW: There is a Willard-30 named "Vega" for sale in Newington, New Hampshire that I might have bought if the Prairie hadn't come along first. It has the advantage of having a much more reasonable size engine (a Yanmar 80 I think) instead of the behemoth 185 Perkins that Rise 'n Shine has. The listing is on Craigslist. Oh, well...

Cheers!

J.S.