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Perkins Diesel Vs Mercruiser Gas Straight Inboard Opinions

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Perkins Diesel Vs Mercruiser Gas Straight Inboard Opinions

Old 10-01-2020, 05:05 PM
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Default Perkins Diesel Vs Mercruiser Gas Straight Inboard Opinions

Getting closer to making the final decision on the next boat. The hulls are all great hulls (25 BHM, 27 Nauset, 28 Cape Dory Fisherman). Each has their perks and downfalls with the individual boats but the main question is the engine. Any one have any thoughts on the engine/hull combo to help guide in the decision? I prefer diesel but know the mercruiser is a good gas engine.

25 BHM 240 Perkins turbo (new turbo 2019) 5XXX hours
27 Nauset 180 Perkins naturally aspirated unknown hours
28 cape dory fisherman mercruiser gas unknown hours

TIA for any thoughts struggling to choose between the 3 each has benefits and downfalls IMO
Old 10-17-2020, 04:45 PM
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My brother had a 28 Cape Dory with a flybridge. The boat really couldn't plane. It was an 8 knot boat. I had a 28ft boat with a perkins 6 cylinder diesel for 4 years. I loved that motor. I would chose one of the diesel boats.
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Old 10-17-2020, 05:00 PM
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Without knowing how far you plan on going on your fishing trips ,how often you go out ,what the difference is in price between the gas and diesels and what you expect to cruise at , your question is impossible to answer. Actual hours can be a deciding factor as well. My suggestion is to take all 3 out. then decide what suits you best.
Old 10-17-2020, 05:01 PM
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Old 10-17-2020, 05:09 PM
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Originally Posted by mr 88 View Post
Without knowing how far you plan on going on your fishing trips ,how often you go out ,what the difference is in price between the gas and diesels and what you expect to cruise at , your question is impossible to answer. Actual hours can be a deciding factor as well. My suggestion is to take all 3 out. then decide what suits you best.

Thats a great point. Fishing will be in New England out of NH from the Portsmouth area to Jeffries ledge. 25-30 miles one way and either drifting humps or anchored tuna fishing so 50-60 mile round trips max. Iím not worried about speed, Iím coming from a center console to a downEast for the comforts of protection and a place to crash if we want to stay fishing overnight or go to the isles of shoals and hang out for a night. 10-14kt Cruise is fine with me.

Prices are all identical, all within $2-3k of each other some have more creature comforts, some have more electronics so all have a trade off on what they have but theyíre all priced in the same ballpark.

Actual hours are not known on two of them. Older gas or inboard diesels Iím not familiar with pulling info from, I donít believe thereís a way to connect anything like a modern 4 strike to pull a log with hours so itís all ok what the engine or owner shows if it says it at all.

Usage would be 200ish hours a year, 2-4 times a week from March/April through November. Combo of haddock, tuna and striper fishing as well as running some lobster traps which is why Iím moving from a CC to a downeast
Old 10-17-2020, 09:03 PM
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I'm not sure which perkens engines but parts for some older models are impossible to find. At a minimum you'll need to find a mechanic to work on them for you, one who can get parts for them.
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Old 10-17-2020, 09:10 PM
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Originally Posted by saltwaters View Post
I'm not sure which perkens engines but parts for some older models are impossible to find. At a minimum you'll need to find a mechanic to work on them for you, one who can get parts for them.
as long as theyíre no the 6.354 with the manicooler, TransAtlantic diesel has always been able to find me parts. The manicooler is an expensive part and hard to find
Old 10-17-2020, 09:23 PM
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The 240 Perkins 6.354 has the aluminum manicooler which can have bad corrosion issues. Expensive to replace or repair. Be cautious if you go that route. The 354 base engine is excellent. The cooler and some other random marine parts can be a bugger.
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Old 10-17-2020, 11:21 PM
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I’d look for one with a Cummins or John Deere motor.
Old 10-18-2020, 03:52 AM
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If you set aside the engine issue, which boat would you choose based on condition, layout, seakeeping, and suitability for what you will be doing? I think that should be the determining factor in this case because it will be a bit of a crap shoot on the engine in any case. The Perkins Diesels are bulletproof for the most part -- if they are now in good shape and never experienced any life shortening mishaps such has having been overheated by a failed impeller that wasn't discovered in time. The Mercruiser gas will be cheaper to fix and cheap to replace with a long block or running takeout but has all the disadvantages of an inboard gas engine. 200 hours per year is a lot of hours for a gas inboard and the fuel cost consideration may become a significant factor, especially if the old Mercruiser is an older inefficient carburetor model and not a newer EFI motor.

With fully mechanical engines, there is no way to track hours short of a working hour meter.

There are a lot of smaller cost items that can add up with an inboard that you would not have experienced with the outboard center console. Are the prop shaft, stuffing box, cutlass bearing, and the propeller itself in good condition? How about the fuel lines and filters and tankage? You don't want expensive surprises. For example, if the prop shaft has become worn at the cutlass, you might face a couple of thousand bucks for a new one. A modern CNC machined propeller that is cleaned and polished and tuned can really make a difference in performance versus an older prop in rough shape.

Last edited by Nomans; 10-18-2020 at 04:06 AM.
Old 10-18-2020, 05:26 AM
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200 hours a year is NOT a lot for gas engines and a 454 /350 that was taken care of should go 4-6000 hours. The difference in diesel fuel cost with the projected hours vs gas would be next to nothing , especially if you take into account the higher price right off the bat for the diesel along with the yearly maintenance and [ in my area ] diesel fuel cost about ,60 more per gallon. I agree it's going to be a whole lot cheaper and probably easier to replace a gasser vs a diesel if it ever comes to that .I can understand the diesel if your running 75-100 miles each way and racking up 5-600 hours a year WITH a heavier ,beamier 30+ hull . In the OPs case I don't see it affecting his operating cost
Old 10-18-2020, 06:58 AM
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Mr 88- Not sure where you are from, but here in the states diesel fuel on the dock is less expensive than gas, usually $1-1.50/gal less. That adds up in 200hrs of run time.
Old 10-18-2020, 07:08 AM
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Originally Posted by mr 88 View Post
200 hours a year is NOT a lot for gas engines and a 454 /350 that was taken care of should go 4-6000 hours. The difference in diesel fuel cost with the projected hours vs gas would be next to nothing , especially if you take into account the higher price right off the bat for the diesel along with the yearly maintenance and [ in my area ] diesel fuel cost about ,60 more per gallon. I agree it's going to be a whole lot cheaper and probably easier to replace a gasser vs a diesel if it ever comes to that .I can understand the diesel if your running 75-100 miles each way and racking up 5-600 hours a year WITH a heavier ,beamier 30+ hull . In the OPs case I don't see it affecting his operating cost
That's not consistent with the facts as I know them. At my fuel dock, gas is $.30 more per gallon. Gasoline engines use significantly more fuel at idle/low rpms than Diesels so depending upon the mix of hours, it would easily be possible to use 100 gallons more per season with gas, which in this area would be $300 per year. That's more than the annual oil and filter change on the motor costs so I think that is material.

The average recreational boat is only used 80-100 hours per year in the Northeast US where the OP lives so 200 hours is in fact a lot by that standard. I agree that the gas engine may well have a lot of hours left before requiring overhaul or replacement. That wasn't my point.
Old 10-18-2020, 09:45 AM
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Thanks for all the helpful tips.

The cape dory with the mercruiser is off the table at this point. The boats in decent shape but the engine isnít installed so itís more of a project boat than Iím looking for and wouldnít be able to sea trial the engine in the hull.

The Perkins is the 240 turbo and Iíve asked the owner about the manicooler but havenít heard back yet. The BHMís seem like the right fit and another popped up with a Volvo TAMD 41 and Volvo transmission. My personal opinion is avoid the Volvo since they have known concerns with that pairing and is comparable in price and cleanliness to the one with the Perkins.

Ill call TransAtlantic diesel this week as they seem to have all the parts and get a feel for some replacement parts cost such as manicooler etc

Old 10-18-2020, 09:52 AM
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Originally Posted by Nomans View Post
That's not consistent with the facts as I know them. At my fuel dock, gas is $.30 more per gallon. Gasoline engines use significantly more fuel at idle/low rpms than Diesels so depending upon the mix of hours, it would easily be possible to use 100 gallons more per season with gas, which in this area would be $300 per year. That's more than the annual oil and filter change on the motor costs so I think that is material.

The average recreational boat is only used 80-100 hours per year in the Northeast US where the OP lives so 200 hours is in fact a lot by that standard. I agree that the gas engine may well have a lot of hours left before requiring overhaul or replacement. That wasn't my point.
Boat is on the west end of Lake Ontario , and the diesel prices on the eastern end of Lake Erie are the same , more than gas. Even with your 300.00 per year how many years is going to take to recoup the extra 10-20.000 +++ that used diesel powered boats go for vs gas in that class of boat ? Rhetorical question.
Old 10-18-2020, 10:08 AM
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I'd have to use Common Core math to ever justify any gas inboard. Even trying to compare outboards to inboard diesels I can't come up with anything other than speed.
Old 10-18-2020, 11:37 AM
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Originally Posted by Corndog38 View Post
Mr 88- Not sure where you are from, but here in the states diesel fuel on the dock is less expensive than gas, usually $1-1.50/gal less. That adds up in 200hrs of run time.
and diesel is much safer. No chance of explosion at the fuel dock or when starting.
Old 10-18-2020, 11:46 AM
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Originally Posted by Jamato14 View Post
Thanks for all the helpful tips.

The cape dory with the mercruiser is off the table at this point. The boats in decent shape but the engine isnít installed so itís more of a project boat than Iím looking for and wouldnít be able to sea trial the engine in the hull.

The Perkins is the 240 turbo and Iíve asked the owner about the manicooler but havenít heard back yet. The BHMís seem like the right fit and another popped up with a Volvo TAMD 41 and Volvo transmission. My personal opinion is avoid the Volvo since they have known concerns with that pairing and is comparable in price and cleanliness to the one with the Perkins.

Ill call TransAtlantic diesel this week as they seem to have all the parts and get a feel for some replacement parts cost such as manicooler etc
between the perkins and Volvo 41, I'd take the volvo. One key is maintenance. MS4 gears can be problematic but mostly if you shift them when not at idle speed. If you shift them at 1.500 rpms you are asking for trouble but that is true of hydraulic transmissions too. Always, always, always shift at idle speeds. Yes, the cone clutch in a volvo gear needs regular maintenance, maybe every 3 years. Find out when it was done (or if). Most guts negect the transmission. There is a guy on the east coast named hans that has a rebuild/exchange program so if the gear hasn't been serviced and it looks like it needs it, hans is the guy to use.

The 41 engine is a good engine, good economy and good power but again, it's all about how well it's maintained. You want to find out if the engine was maintained by a mechanic and if things were done. Check the exhaust system install. Many boats with low bilges (down east type) don't have the proper spill over height to keep water from back flowing into the turbo. If you see a lot of rust where the exhaust elbow attaches to the turbo, that turbo ingested water. It can be fixed with a new turbo but the exhaust system will require a redesign and new piping.
Old 10-18-2020, 12:08 PM
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Originally Posted by mr 88 View Post
200 hours a year is NOT a lot for gas engines and a 454 /350 that was taken care of should go 4-6000 hours. The difference in diesel fuel cost with the projected hours vs gas would be next to nothing , especially if you take into account the higher price right off the bat for the diesel along with the yearly maintenance and [ in my area ] diesel fuel cost about ,60 more per gallon. I agree it's going to be a whole lot cheaper and probably easier to replace a gasser vs a diesel if it ever comes to that .I can understand the diesel if your running 75-100 miles each way and racking up 5-600 hours a year WITH a heavier ,beamier 30+ hull . In the OPs case I don't see it affecting his operating cost
In the US, Diesel is significantly cheaper in most areas. Additionally, all things being even, diesel will get you ALOT more life than a gas engine. Besides the safety concerns with gas inboards as well especially on an old boat. If you're going to get an old one, get a diesel. Unknown hours gas? You can be in for a major rebuild sooner than you think. A diesel maintained well will go 5-6x longer than a gas engine before it needs any "rebuild". Additionally, its a myth that diesel is significant more yearly maintenance. Total myth, I promise you that.
Old 10-18-2020, 02:24 PM
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Originally Posted by saltwaters View Post
between the perkins and Volvo 41, I'd take the volvo. One key is maintenance. MS4 gears can be problematic but mostly if you shift them when not at idle speed. If you shift them at 1.500 rpms you are asking for trouble but that is true of hydraulic transmissions too. Always, always, always shift at idle speeds. Yes, the cone clutch in a volvo gear needs regular maintenance, maybe every 3 years. Find out when it was done (or if). Most guts negect the transmission. There is a guy on the east coast named hans that has a rebuild/exchange program so if the gear hasn't been serviced and it looks like it needs it, hans is the guy to use.

The 41 engine is a good engine, good economy and good power but again, it's all about how well it's maintained. You want to find out if the engine was maintained by a mechanic and if things were done. Check the exhaust system install. Many boats with low bilges (down east type) don't have the proper spill over height to keep water from back flowing into the turbo. If you see a lot of rust where the exhaust elbow attaches to the turbo, that turbo ingested water. It can be fixed with a new turbo but the exhaust system will require a redesign and new piping.
Thats great info, thanks for the tips. Iíll see if I can find Hans and have a conversation with him. Do you have any idea on his location or a way to find his contact info?

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