Reply
 
Thread Tools Display Modes
 
Old 11-29-2013, 11:41 PM   #1
Al
Guru
 
Al's Avatar
 
City: ketchikan, Alaska
Country: usa
Vessel Name: 'SLO'~BELLE
Vessel Model: 1978 Marben-27' Flybridge Trawler Pilothouse Pocket Cruiser[
Join Date: Apr 2012
Posts: 1,690
Luxury on a miser budget

I'd ask a moderator if this is the forum for this subject, As it covers several on going conversations regarding running one engine of twins, increasing or decreasing prop dimensions, fuel burn, Slow speed (6.5-7.5 knots) and other associated subjects it is not easy to pick a forum to post this.

During several conversations on gas vs diesel power or re-power the lack of this thought has not been forthcoming or at least not in recent forums that have been monitored. So here is the concept.

On the market there are currently many larger size boats that are powered with twin 454 gas or similar. These boats are on the market quite reasonably priced for the value within. I use as an example the following example:
Tollycraft Sedan Bridge 37

Here we have a 34 foot boat with twin engines at a very good price. Under the concept being discussed would be the re-powering of the boat with twin inexpensive diesels
Likewise, if one reads the Christ Craft forum, one finds the perfect platform in even larger boats that beg for such a conversion concept.

for this discussion offered are three current Ebay advertisements for same model/make engines.

Perkins 4.108 Diesel Engine Marine Industrial Generators eBay

Perkins 4 107 Diesel Engine Marine Kholer Generator | eBay

Perkins 4 107 Diesel Engine Marine with Transmission Sailboat Take Off | eBay


Combine the price/shipping/tear out/re-place cost with two of the above engines plus the price of the boat seemingly would present an opportunity to obtain the stately finishings of a modern large boat at a very attractive investment amount.

There, a long running frustration put to print for discussion if warrented.

Al- Ketchikan (Bridge to Nowhere) Alaska
__________________
Advertisement

Al is offline   Reply With Quote
Old 11-30-2013, 12:09 AM   #2
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,360
There is nothing inexpensive about converting a gas to diesel. Assuming a Cummins reman and twins, the total price will easily top 70K and take a very long time. Best to find that diesel diamond in the rough. PMM had A very complete article 3 years ago on converting a 34 Tolly using Volvos. Peruse the boatdiesel archives and you'll find many cost to convert discussions.

But, I know a few people who have great DIY skills and the challenge appealed to them. The nicest conversions I've seen are for the Tolly 44. The boats were designed for gas or diesel V8s so a straight 6 diesel really opens up the ER.

BTW, buying a marine diesel on eBay sounds dicey to me.
__________________

sunchaser is offline   Reply With Quote
Old 11-30-2013, 12:22 AM   #3
Al
Guru
 
Al's Avatar
 
City: ketchikan, Alaska
Country: usa
Vessel Name: 'SLO'~BELLE
Vessel Model: 1978 Marben-27' Flybridge Trawler Pilothouse Pocket Cruiser[
Join Date: Apr 2012
Posts: 1,690
Sunchaser- Thanks, Let me redefine the goal. (1) Purchase a 454 twin powered craft wood or plastic. Price is low due to expense of running the hull at semi or at full planing speed because the owner is not into slow speed. and the boat is now a hard sell on the market. (2) Trawler speed boater seeking the max amount of boat that he can drive at trawler speed. No need for reman Cummings that being the reason of showing the cost of two small 50 hp diesels with low price.
The goal is to move a 34-45 foot semi displacement boat at a comfortable 6.5 knots.without spendy fuel cost or cost as you laid out. The end result of the process having maximum comfort of the luxury accommodations.
Hope this gives a little more direction of the concept.
Thanks,
Al
Al is offline   Reply With Quote
Old 11-30-2013, 06:07 AM   #4
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,515
The question is not parts $$$ its LABOR $$$.

A DIY can do most anything although a plaining boat at low speeds will never be as comfortable , stable as a hull designed as full displacement at displacement speeds , nor as efficient..

You can swop the engines , but not the ride.

To do it at the lowest cost I would first find out the SAE bellhousing size of the existing engine , with a mind to install a diesel or two and hopefully keep the tranny , shaft and prop.

I would look at inexpensive engines , the International DT 360 and 466 are dirt cheap at the truck wreckers , cheap to rebuild and are mechanical or electric injection as you chose. $3000 to $5000 per almost new..

You will need a heat exchanger and exhaust elbow

Second choice would be a MODERN set of OTS marinized gas engines of a smaller size.

The 305 are not expensive , and a deeper reduction tranny could spin the big wheels with only a loss in top speed.

This would probably make the best swop , as you would have gas priced maint and repair bills. The boat could probably semi plane (at massive fuel cost) too stabilize it for a get home in nasty weather.

Most of the time low rpm and noise would be a great cruising boat.

A small diesel would be last choice as it would have no reserve power , and makes diesel racket and uses diesel priced parts , oil and antifreez. Tho it would get the best , lowest fuel burn cruising.

For a cruiser a single would be preferred , only one engine to mess with and the protected props will help in every grounding.
FF is offline   Reply With Quote
Old 11-30-2013, 06:14 AM   #5
Guru
 
healhustler's Avatar
 
City: Longboat Key, FL
Country: USA
Vessel Name: Bucky
Vessel Model: Krogen Manatee 36 North Sea
Join Date: Oct 2009
Posts: 4,178
I don't know of such a case, and I'd say that it is an interesting concept, but it would have to be a disciplined one to make it result in the product you want. I'd surely want to find already marinized diesels to start with, and then find myself a comfortable cruiser that, as FF points out above, has a good trawler ride. All the gas to diesel conversions I know of were with owners that sought to get similar performance out of the hull. I'd sure want to start with a hull that trips my trigger though....not knowing what the market would be for the final product.

You know, it's too bad that even though the concept has merit for resourceful guys with enough boat knowledge to do their one-off creations, sales marketing and public ignorance would likely prevent the practice from ever becoming trendy enough to support a new "conversion" industry like we had with trucks in the 50's and early 60's.
__________________
Larry

"I'd rather be happy than dignified".
healhustler is offline   Reply With Quote
Old 11-30-2013, 06:38 AM   #6
Guru
 
timjet's Avatar
 
Join Date: Apr 2009
Posts: 1,905
Quote:
Originally Posted by FF View Post
The question is not parts $$$ its LABOR $$$.

A DIY can do most anything although a plaining boat at low speeds will never be as comfortable , stable as a hull designed as full displacement at displacement speeds , nor as efficient..

You can swop the engines , but not the ride.
You might want to heed that advice. My semi-planning hull requires a lot of steering inputs to steer a course at displacement speeds. Surprisingly the autopilot does a pretty good job at slower speeds, but I don't use the autopilot in narrow channels.
__________________
Tim
Tampa Bay
Carver 355 ACMY Twin Cummins Diesels Sold
timjet is offline   Reply With Quote
Old 11-30-2013, 07:22 AM   #7
Guru
 
Forkliftt's Avatar
 
City: Biloxi Mississippi
Country: USA
Vessel Name: Patricia Louise II
Vessel Model: 1983 42' Present Sundeck
Join Date: Oct 2007
Posts: 2,433
I think the idea has merit. As FF mentioned, the SAE flywheel pattern should be determined first, and then use an engine that bolts up to this. Allows you to reuse marine gear and shaft. First job would be to fabricate motor mounts then install and align engine.
__________________
Steve Point Cadet/ Biloxi, Mississippi USA
*Present 42 twin 135 Lehmans
Forkliftt is offline   Reply With Quote
Old 11-30-2013, 10:05 AM   #8
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,360
No doubt what Al and FF are bringing up can be done. But take out the word LUXURY from the title and call it back yard project or the like.

Thirty years ago some fellows built their version of luxury on the Mississippi near St Charles. They took a 1960s Cadillac and with great ingenuity mounted it on a carefully crafted small steel hull. The prop was driven by the drive line through a not well thought out shaft tube that sprung a big leak, sinking the vessel and drowning the two builders.

Buying cheap and building cheap certainly works and can result in great rewards. But lots of owner sweat and know how is involved.

FF, I very well know of International's engines from the 1970s, but does anybody use them today for a drop in marine replacement? They are big, heavy and parts challenged. Can do and will do are two different things.
sunchaser is offline   Reply With Quote
Old 11-30-2013, 10:58 AM   #9
Guru
 
Join Date: Aug 2012
Posts: 741
As previously mentioned, in addition to an SAE bell housing bolt pattern, the availability of heat exchangers and exhaust manifolds probably define the viability of a given engine. Mesa Marine (www.mesamarine.com) has an excellent on-line catalogue of aftermarket exchangers and manifolds for a wide range of diesels. The Isuzu four and six cylinder truck engines and the ubiquitous Cummins look like good candidates for low power marine conversions.
Underway is offline   Reply With Quote
Old 11-30-2013, 11:07 AM   #10
TF Site Team
 
Bay Pelican's Avatar
 
City: Chicago, IL
Country: USA
Vessel Name: Bay Pelican
Vessel Model: Krogen 42
Join Date: Oct 2007
Posts: 2,781
Quote:
Originally Posted by Al View Post
[FONT=Arial][SIZE=2][FONT=Comic Sans MS][SIZE=4][COLOR=#008000][B]I'd ask a moderator if this is the forum for this subject,

Certainly trawler related.

Marty
Bay Pelican is offline   Reply With Quote
Old 11-30-2013, 01:46 PM   #11
Senior Member
 
City: Ft Lauderdale
Country: USA
Vessel Model: 120' Custom, Cat 3512's, 1750 HP ea.
Join Date: Nov 2013
Posts: 159
I've been thinking along these same lines/concept for a while now. Still in the research stage but liking the idea. Thats actually why I joined this forum, to get ideas on small boat cruising info. I have a mid 90's 50' production hull in mind. The hulls are plentiful and reasonably cheap to buy, as they're all due for a refit and the engines are mostly older, heavy, worn out fuel guzzelers and due for rebuild or replacement anyway. Rip out the old lumps and replace with a more modern, low power pair. End up with a nice wide body, shallow draft, economical coastal cruiser, perfect for running up and down the intercoastal. Rough numbers right now show after the first Florida/New England round trip you'd about break even, except you'd own the conversion as opposed to burning it in fuel. And reliability would increase dramatically,as would work space in the engine room.
It would be pretty purpose specific so re-sale might be an issue, but keep the old engines and it would be an easy swap back.
BerettaRacer is offline   Reply With Quote
Old 11-30-2013, 02:29 PM   #12
Senior Member
 
slowandsteady's Avatar
 
City: North Kingstown, RI
Country: USA
Vessel Model: Mainship 34 III
Join Date: Jul 2013
Posts: 151
In my opinion the perfect boat for this would be the Mainship DC 36 or 40. Lots of boat for the money, semi displacement hull with twin 350 and 454. Many of them out there. Swap the engines with diesels but then what about the genset? I thought about it, but not too long.

Sent from my iPhone using Trawler
slowandsteady is offline   Reply With Quote
Old 11-30-2013, 02:46 PM   #13
Senior Member
 
ronlord's Avatar
 
City: Grand Island NY
Country: US
Vessel Name: Missy
Vessel Model: Mainship 350
Join Date: Jun 2013
Posts: 163
That Tolly is sweet for only 14k. It has rebuilt engines and a diesel genny, why would you think about repowering? At hull speed that boat will probably get around 1.5 mpg, you could buy a heck of a lot of gasoline for what it would cost to repower with diesel. Just because it has gas engines and can plane doesn't mean you have to... Those engines will run just fine at 1500 rpms, burning modest amounts of fuel.
ronlord is offline   Reply With Quote
Old 11-30-2013, 03:25 PM   #14
Al
Guru
 
Al's Avatar
 
City: ketchikan, Alaska
Country: usa
Vessel Name: 'SLO'~BELLE
Vessel Model: 1978 Marben-27' Flybridge Trawler Pilothouse Pocket Cruiser[
Join Date: Apr 2012
Posts: 1,690
BerettaRacer and Ronlord seemingly have come the closest to reflecting the goal.
As to measuring bell housings and such to retain the current reduction gears. It would not be worth the effort, most 454' or gas engines in general in these situations, as they will be below the required ratio for a small Perkins marine fitted engine as the examples given were. It would be thought that at the very least a 3:1 gear ratio required to swing the existing wheels on these gas pot applications.
As an example our boat (27 foot) has a 3:1 gear on a 58 hp Perkins with a 22X16 LH wheel driving it at hull speed of 6.5/7 knots at 2400 RPM. Assuming a boat in the 35-45 foot range with twin 58 hp Perkins, Yanmar, Volvo,Ford engines would achieve a similar result.
As to the ability of a planning hull underway for steerage. From actual usage of a 28 foot Christcraft l960's plywood planing hull where we did run the gas pot at 1500 RPM, enjoyed without any noticeable steering complications. In a following sea, ALL the boats owned by our family (Many!) experience the usual following sea habits.
At any rate, yes, the concept should be studied by as noted, "Backyard" boaters who have the time and inclination to undertake a project. Not being affluent as some, the concept was intended in part for "dreamers" of what could be when dollars are not available for the purchase of a similar finished first class model.
Thanks for the comments and response. Makes the Forum a hoot!!
Al
Al is offline   Reply With Quote
Old 11-30-2013, 04:03 PM   #15
Guru
 
dhmeissner's Avatar
 
City: Seattle
Country: North America
Vessel Name: The Promise
Vessel Model: Roughwater 35
Join Date: Sep 2012
Posts: 1,325
Quote:
Originally Posted by ronlord View Post
That Tolly is sweet for only 14k. It has rebuilt engines and a diesel genny, why would you think about repowering? At hull speed that boat will probably get around 1.5 mpg, you could buy a heck of a lot of gasoline for what it would cost to repower with diesel. Just because it has gas engines and can plane doesn't mean you have to... Those engines will run just fine at 1500 rpms, burning modest amounts of fuel.

What he said. And a heck of a lot of red wine.
__________________
Dave & Suzie - Roughwater 35
http://thepromiserwb1029.org/2012/09...the-promise-2/
dhmeissner is offline   Reply With Quote
Old 11-30-2013, 04:17 PM   #16
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,515
>Rip out the old lumps and replace with a more modern, low power pair.<

RIP OUT is the first challenge , many boats have no hatches above the engine , so a hot knife or cut off set will have to reduce the block to 100lb removable pieces, after everything that could be unbolted has been discarded..

Sliding any engine , even a car donor transplant back down a companionway , may call for a bunch of stripping and a pile of buddies, and BEER!

While International may have been in business for 7 decades , today there called Navstar , and they produce the DT line of engines today.

http://en.wikipedia.org/wiki/Navistar_DT_engine
FF is offline   Reply With Quote
Old 11-30-2013, 06:08 PM   #17
Senior Member
 
City: Ft Lauderdale
Country: USA
Vessel Model: 120' Custom, Cat 3512's, 1750 HP ea.
Join Date: Nov 2013
Posts: 159
Quote:
Originally Posted by FF View Post
>Rip out the old lumps and replace with a more modern, low power pair.<

RIP OUT is the first challenge , many boats have no hatches above the engine , so a hot knife or cut off set will have to reduce the block to 100lb removable pieces, after everything that could be unbolted has been discarded..

Sliding any engine , even a car donor transplant back down a companionway , may call for a bunch of stripping and a pile of buddies, and BEER!
The hull that I'm looking at the engine access is a simple matter of unbolting the cockpit seats, lifting the hatches and unbolting the strengthening ribs, voilla!!
A side benefit, the old engines are 36-3800 lbs each, the Cummins I'm looking at for replacement are 1200 lbs ea, thats over a 4500 lb savings in the aft end of the boat. And I'm going from diesel to diesel, very little incompatability issues, pretty much just some smaller wheels. But again, still in the research process at this point.
BerettaRacer is offline   Reply With Quote
Old 11-30-2013, 07:03 PM   #18
Art
Guru
 
Art's Avatar
 
City: SF Bay Area
Country: USA
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 7,979
Good Golly Molly!! - IMVHO!!

Unless you simply like to spend money and/or work REAL hard for hundreds of hours: Just locate a real good condition pleasure trawler/cruiser and do what these play-boat craft were meant to be for - i.e. "Pleasure Boating, Cruising, Hooking, Gunkholing, Swimming, Relaxing, Partying... etc!"

Art is offline   Reply With Quote
Old 12-01-2013, 06:15 AM   #19
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,515
>pretty much just some smaller wheels. <

Perhaps , I would purchase a good tach gun , mark the shaft and use a GPS to create a log of shaft RPM vs boat speed.

Every 25 RPM .

The shaft speed might be low enough at 7K or so that a deep reduction on the replacement could allow the same prop to be kept.

MOST of these smaller engines are far lighter duty than a real industrial or large truck engine .

Something like a 4-107 will not live at 2400 RPM as cruise RPM, work out the piston speed and keep it modest.

IF the GPH at the new desired cruise speed can be found from the old engine , gas or diesel, the estimate of how much HP will be required would be far easier.

IF any of this was easy , hundreds of fine old boats would have been done already.

That there NOT done , should cause one to wonder why decades of folks choose not to do it.

CAVIAT EMPTOR
FF is offline   Reply With Quote
Old 12-01-2013, 02:12 PM   #20
Al
Guru
 
Al's Avatar
 
City: ketchikan, Alaska
Country: usa
Vessel Name: 'SLO'~BELLE
Vessel Model: 1978 Marben-27' Flybridge Trawler Pilothouse Pocket Cruiser[
Join Date: Apr 2012
Posts: 1,690
FF you make my point there are I suppose, "Hundreds" of said boats that would serve as platforms for such a change. Economics have a part. The vast majority of boaters are currently able to purchase a boat that fits their economic status. Others not so much and with the potential of becoming a third world country maybe so.
There is then a large segment of boating community that has no desire or ability to overcome the lack of economic status to venture into such a project.
Yes, agreed the field of participants would at the current point in time, be slight. However, with that stated "Hundreds" of boats, with large gas engines laying about unused and deteriorating, the potential of obtaining one, spending sweat and labor of removing the current power plants, obtaining two SMALL marine diesels with higher (3:1 or more) to allow turning the current wheels.

Now- as to the RPM issue. The 4-107 Perkins has a recommended WOT of 2600/2800 RPM +/- (Not quite sure without looking the difference of 200 RPM up)

You continue to use "Truck engines" seemingly ignoring that these Perkins used as an example, exist in the multitudes as current marine engines, Yes they are "Small" however proven. Yes they are the same blocks and such, but the maritime apparatuses that are involved are in place and the engines are marine, not truck.

The 454 gas most likely has a 1:5/1 or 2:-1 gear ratio.and a WOT of 4000 RPM.
Theoretically they could run at WOT however nobody would as they would in a short time be stressed to destruction.
So there are extremes that exist but are not used as norms

I'd make a guess that a 40 foot say Chris Craft, with twin 454s would cruise at 8-8.5 knots around 1800 RPM. (subject to confirmation or challenge by a similar described boat owner reading). If the reduction gear is a 2:1 the wheels are turning around 900 RPM. The Perkins with a 3:1 would be turning the wheels at 600 RPM.(I'd venture you could turn the 4-107 at 2000 RPM) I'd guess a 6 knot speed would result. That being said and willingly open to some mathamatical marine engineer type.

Yes, you have little spare power should you require it. Yes, there are challenges that would require pre and during voyage considerations with this, however, you are on the water living in uncommon luxury above your pay grade, and moving. Slow, but moving.

The desire and personal ability available with limited resources make for a lively discussion. Hence the submission to the Forum.

Enjoying the thread FF you have a way of making them interesting. Anticipate your enlighten thoughts.
Al[/B][/I][/COLOR]
__________________

Al is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 09:24 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012