Boat Engines
 

Hi there

I have been looking at the UK market for a 75HP marine inboard engine. Those
that look good are products from Volvo, Betamarine and Lombardini, but what
a price!. I struggle with the fact that my new car cost less than one of
these and that got me to thinking if I could do it myself.

What are the pitfalls in "marineising" a good used truck engine, are
aftermarket kits sold and what about marrying the gearbox to the engine bell
housing.

I seem to recall reading a thread on this subject some years back, but at
the time I was not too interested. Now of course I cannot find threads going
that far back.

TIA

Steve

Boat Engines
 

It can be done very successfully, but not by an amatuer. The duty cycle of
an automotive engine is around 30%. Marine engines require a 100% duty
cycle. Converting an automotive engine to marine involves far more than just
cooling system and exhaust. However there are firms that sell conversion
kits that do a reasonably good job without extensive engine mods, but be
careful. Under no circumstance will you ever be able to open up the trottle
and run the boat in that manner, because the engine will self destruct.
Steve

"Steve Morrisby" wrote in message
...
Hi there

I have been looking at the UK market for a 75HP marine inboard engine.
Those
that look good are products from Volvo, Betamarine and Lombardini, but
what
a price!. I struggle with the fact that my new car cost less than one of
these and that got me to thinking if I could do it myself.

What are the pitfalls in "marineising" a good used truck engine, are
aftermarket kits sold and what about marrying the gearbox to the engine
bell
housing.

I seem to recall reading a thread on this subject some years back, but at
the time I was not too interested. Now of course I cannot find threads
going
that far back.

TIA

Steve

Boat Engines
 

It's been talked to death.

you will need a foreward and reverse thrust bearing, wrong gearing,
spark proof alternator, and a wet exhaust system.

If you can get 2 or 3 old 318's, run 'em till they burn out, and
rebuild the dead ones over the winter.

With any luck, thay won't last long enough to rust or electrolyze out.

Terry K

Boat Engines
 

Steve Morrisby wrote:
Hi there

I have been looking at the UK market for a 75HP marine inboard engine. Those
that look good are products from Volvo, Betamarine and Lombardini, but what
a price!. I struggle with the fact that my new car cost less than one of
these and that got me to thinking if I could do it myself.

What are the pitfalls in "marineising" a good used truck engine, are
aftermarket kits sold and what about marrying the gearbox to the engine bell
housing.

OT: it would be easier imo to get a used marine engine, tear it down,
and rebuild it ... than to buy all those marine parts (wet exhaust
parts etc etc) you'd have to get to bolt onto that truck engine.

Boat Engines
 

It's been talked to death.

you will need a foreward and reverse thrust bearing, wrong gearing, and
a wet exhaust system.

If you can get 2 or 3 old 318's, run 'em till they burn out, and
rebuild the dead ones over the winter.

With any luck, thay won't last long enough to rust or electrolyze out.

Terry k

Boat Engines
 

On Fri, 08 Dec 2006 20:25:06 GMT Steve Morrisby
) wrote:

I have been looking at the UK market for a 75HP marine inboard engine. Those
that look good are products from Volvo, Betamarine and Lombardini, but what
a price!. I struggle with the fact that my new car cost less than one of
these and that got me to thinking if I could do it myself.

That's possible, but remember above companies sell complete products,
e.g. engine, cooling system, gearbox and control panel.

What are the pitfalls in "marineising" a good used truck engine, are
aftermarket kits sold and what about marrying the gearbox to the engine bell
housing.

Used gearboxes are rare, bell housings even more, you'll pay full for
them. I know what I'm talking about: the single coupling to replace the
old worn coupling http://qatsi.ath.cx/cgi-bin/foto/438/76.jpg is half
the price the used gen-set http://qatsi.ath.cx/cgi-bin/foto/401/06.jpg
did cost.

I seem to recall reading a thread on this subject some years back, but at
the time I was not too interested. Now of course I cannot find threads going
that far back.

Buying a complete second had engine would be the easiest option, doing
it all yourself can be fun if you like it.

--
Richard
e-mail: vervang/replace invalid door/with NL.net
http://web.inter.nl.net/users/schnecke/

Boat Engines
 

That makes me wonder if it would be possible to keep the engine
air-cooled and exhausted through a dry stack, perhaps by fitting a
bigger radiator and using forced-air cooling ducts.

To get around the gearbox problem, why not couple the engine to a
hydraulic pump and use a hydraulic motor with a thrust bearing to drive
the prop shaft? With a short run of hose, I don't know if the energy
lost would be great. You could use your main engine to power a bow
thruster that way, too.

Just a thought.

-Max Camirand


Terry K wrote:
It's been talked to death.

you will need a foreward and reverse thrust bearing, wrong gearing,
spark proof alternator, and a wet exhaust system.

If you can get 2 or 3 old 318's, run 'em till they burn out, and
rebuild the dead ones over the winter.

With any luck, thay won't last long enough to rust or electrolyze out.

Terry K

Boat Engines
 

Ah yes!. I did not consider that the marine engine is continuous duty. Considering that fact the cost is probably justified.

Referring to Max Camirands posting, I also wondered about air cooling. Deutz built a fine range of air cooled engines, and it would keep the boat nice and warm!. But I am still up against the continuous duty problem.


Thanks for all your input.

Steve



"Richard van den Berg" wrote in message ...
On Fri, 08 Dec 2006 20:25:06 GMT Steve Morrisby
) wrote:

I have been looking at the UK market for a 75HP marine inboard engine. Those
that look good are products from Volvo, Betamarine and Lombardini, but what
a price!. I struggle with the fact that my new car cost less than one of
these and that got me to thinking if I could do it myself.

That's possible, but remember above companies sell complete products,
e.g. engine, cooling system, gearbox and control panel.

What are the pitfalls in "marineising" a good used truck engine, are
aftermarket kits sold and what about marrying the gearbox to the engine bell
housing.

Used gearboxes are rare, bell housings even more, you'll pay full for
them. I know what I'm talking about: the single coupling to replace the
old worn coupling http://qatsi.ath.cx/cgi-bin/foto/438/76.jpg is half
the price the used gen-set http://qatsi.ath.cx/cgi-bin/foto/401/06.jpg
did cost.

I seem to recall reading a thread on this subject some years back, but at
the time I was not too interested. Now of course I cannot find threads going
that far back.

Buying a complete second had engine would be the easiest option, doing
it all yourself can be fun if you like it.

--
Richard
e-mail: vervang/replace invalid door/with NL.net
http://web.inter.nl.net/users/schnecke/

Boat Engines
 

On Mon, 11 Dec 2006 11:05:13 GMT Steve Morrisby
) wrote:
[-- text/plain, encoding quoted-printable, charset: iso-8859-1, 56 lines --]

Ah yes!. I did not consider that the marine engine is continuous
duty. Considering that fact the cost is probably justified.

That's open for discussion.;-)

Referring to Max Camirands posting, I also wondered about air
cooling. Deutz built a fine range of air cooled engines, and it would
keep the boat nice and warm!.

If you like the engineroom smell, then it's allright, it's not my
choice. Running airducts is a matter of space, gen-sets are somehow that
way built.

But I am still up against the continuous duty problem.

I see that more as a sale/warranty figure. A displacing ship with more
than 5 hp/ton has enough power, equipped with the right prop of course.

--
Richard
e-mail: vervang/replace invalid door/with NL.net

Boat Engines
 

If air cooling didn't work out, you could remove the radiator and
instead pump the coolant through a coil of copper pipe running through
a sea chest (small seawater-flooded compartment built inside on the
inside surface of the hull). Kind of like a keel cooler, but inside.
The advantage over cooling with raw seawater is that you don't get
corrosion inside your engine, both from the seawater and from the
galvanic action it creates between the dissimilar metals in the engine.
Of course, it's slightly more complicated.

I'm not sure that I understand the continuous duty problem. Certainly,
truck engines aren't meant to run at 100% of rated RPM all the time.
However, they can do long 'passages' at highway loads, which (I think)
is around a third of rated HP. Truckers even leave their engines
turning at high idle while they're stopped. Why wouldn't you use a
400hp truck engine as a 100hp boat engine? If yours is a big ol' boat
running at displacement speeds, the difference in weight wouldn't
matter much. Anyway, I got the impression that when manufacturers sold
an engine as "continuous-rated" versus "intermittent-rated", half the
difference was simply reducing the rated HP. I could easily be wrong.

I've never done this sort of thing. I'm just thinking about how I'd do
it if I were in a 'gypsy' frame of mind, and I wanted a decent boat for
minimum cost. What do you experienced folk think?

-Max Camirand

Steve Morrisby wrote:
Ah yes!. I did not consider that the marine engine is continuous duty. Considering that fact the cost is probably justified.

Referring to Max Camirands posting, I also wondered about air cooling. Deutz built a fine range of air cooled engines, and it would keep the boat nice and warm!. But I am still up against the continuous duty problem.


Thanks for all your input.

Steve