Inboard engine idea

[Dieselboatman]

I can get due to my trade (diesel mechanic and ex agricultural engineer) all manner of diesel engines and gearboxes easily enough from cars and Van's

I am interested in a colvic 20 or seaworker and have seen a bare hull colvic 20 which still tempts me

Now I know usual setup is a marinised engine, and a marine gearbox (£200 plus?)

What's stopping me from using a car/van gearbox?

I know I would need a thrust bearing, but that's no problem

Was just thinking as I can get a complete engine and gearbox from a car/van for next to nothing

Either a Transit 2.5Di with a manual gearbox, or occasionally something like a Mercedes diesel with an auto box

Obviously mounting it is not an issue, and then would link it to the thrust bearing using a modified car propshaft, and then an adaptor to drive the boat prop/shaft

What about the clutch? Would it need the vehicle manual clutch connecting? Could do cable or hydraulic easily to a lever if needed

Just thought it would be an easy way for me to get a gearbox, it would have reverse and several forward speeds including an over drive ratio (so even if limited by hull speed, could drop into overdrive to drop rpm for fuel economy)

Reverse would be slow admittedly (most car/van boxes have a 2.5~3.5:1 ratio) but then would have a selection of forward speeds

Manual box would require linkages making to move the selector (unless already cable change) and the auto would have cable or electronic selection

But I'm not too worried about that side of it

What about the torque converter on an auto? Or the clutch plate on a manual?

Would they need modification?


Just an idea overall, I know boats arent cheap no matter what, but obviously modifications and custom mounts etc will cost me next to nothing

And it would save having to buy a marine gearbox and possibly making or buying an adaptor plate to mate with engine



Exhaust I have been weighing up options and have decided a dry stack heavily wrapped and then surrounded by a length of stainless flue would be fine for my purpose

I would ideally like to have little/no raw water being pumped around

I have been researching about 'keel' cooling as an option as well but haven't found any pictures of a setup on a boat, only discussions about it

 

[Tamar]

Nothing at all, when I started boating around 40 years ago there were all manner of car/ van engines in boats, my last boat had a marinised montego diesel coupled to a marine GB. Don't think you will need a thrust bearing as the engine mounts will do, although it would be a good idea. There will be someone along soon more knowledgeable than me
Good luck

 

[cherod]

montego i believe was called a perkins prima in a boat ??? had quite a good reputation from what i recall .. no idea about g/box

 

[Motor_Sailor]

The lobster boats in Maine all used to run car engines (big block V8s with dry stacks and keel cooling. On a still day, you could hear them from Cornwall when they all left together on the morning tide.

Keel cooling with a GRP boat needs some sorting out as you'll be surprised by the area required. I'm sure the tables for cooler surface area / seawater temperature / engine horsepower will be online somewhere. Keel cooling is regularly used in canal boats but as part of the steel hull. You will probably need an external water pump as the internal one on the engine doesn't really have the capacity to move the coolant through the extra lengths of piping.

The marine gearbox is a different matter - I haven't seen the successful use of a vehicle box (but there may be). However I don't think finding a suitable marine box wouild be too expensive. If using a Ford engine, Lancing Marine have always been the 'go-to' people for bits.

 

[Rappey]

Seen a boat with car engine and gearbox. No idea how well it worked.
An auto box may overheat due to lack of cooling.
Saw a speedboat with a v8 and two large fan cooled radiators.. guy said it worked great.

 

[Motor_Sailor]

montego i believe was called a perkins prima in a boat ??? had quite a good reputation from what i recall .. no idea about g/box

Yes the Montego ( Sherpa Van, plus very early Freelanders) was a Perkins Diesel which became the Volvo MD22L (with their own gearbox). You might very well find a suitable gearbox from these. I've just dumped a perfectly good one in for recycling off a blown engine as no one wanted the gearbox.

 

[PCUK]

I've got a marine Ford 4d with PRM gearbox. It's in bits as I stripped it and never got round to the rebuild. Bores are all good. Comes with new pistons and shells. Just needs assembling. Piece of cake for you to do. PM me if you'd like to discuss It. Based in Devon near junction 27 M5. Far better than an ex van mish-mash!

 

[BruceK]

Gearbox: Two reasons not to. Your prop is already set for max efficiency (max rpm gained for max speed achieved. i,e, top gear) so all you can do is reduce the gear ratio to get on the plane quicker if that is even necessary. For that purpose there has been some experimentation of 2 gear boxes, ZF being most notable but never really all that popular.
Boats have a lot of drag, there is absolutely no freewheeling. By the time you have selected a higher gear you've already dropped enough speed so you cant effectively use it (when lessening a gear ratio)

Marinising an engine isn't just about cooling. The engine needs to develop torque differently so it's also a head, valve, timing and fuel jobbie. By the time you've finished you will probably pay more than off the shelf.

Your idea isn't new. Everyone has thought about it. That it hasn't been done speaks volumes, with very few exceptions. The main exception is with large boats where you run on the same principle of a diesel loco. Get the engine at a max torque rpm and then through a gearbox to a generator which in turn supplies a electric motor to drive the boat.

 

[scottie]

Have a look at lancing marines website
https://r.search.yahoo.com/_ylt=Awr...ine.com//RK=2/RS=eXV.qgXPH.B6N6VTMA1hOTEOL3M-
They have done it all for you
Automotive gear boxes don’t really work that well as the ratios are different in fwd Rev so propeller works one or other
Heat is your enemy or at least trying to get rid of it
A combined manifold and header tank is the current way for good reasons neither dry exhaust nor keel cooling is convenient or perhaps even safe in a small boat
The industry has moved on in the last 50years
With regards to thrust marine boxes are designed to cope with that
I am sure that you’d have the ability to fabricate adapter plates and mounting feet bearers etc
Good luck

 

[Dieselboatman]

I can make an adaptor if needed, and likely will then! It was just a though as I can always get car/van gearboxes

I will just fabricate an adaptor or even do a remote gearbox if needed....

As for the Perkins Prima, brilliant little engine, very popular in the old series 1 and 2 land rovers as well, but sadly all are getting long in the tooth
It was the basis for the rover L series diesel which replaced it (freelander etc)

As for keel cooling it was more a curiosity question really, I think the easiest setup will be an indirect raw water cooled with a heat exchanger then

As for dry stack, i know they arent as popular but unless I couldn't safely fit one due to routing etc, I would prefer it


As for a marine diesel having its torque output at a different rpm etc, that's easily solved especially with a turbo diesel, either by altering fuelling to spool turbo quicker, adjusting vanes on a variable geometry turbo, or by stiffening wastegate preload.
Or indeed changing turrbocharger for a different size

(Done an awful lot of diesel tuning in vehicles)

 

[volvopaul]

I can get due to my trade (diesel mechanic and ex agricultural engineer) all manner of diesel engines and gearboxes easily enough from cars and Van's

I am interested in a colvic 20 or seaworker and have seen a bare hull colvic 20 which still tempts me

Now I know usual setup is a marinised engine, and a marine gearbox (£200 plus?)

What's stopping me from using a car/van gearbox?

I know I would need a thrust bearing, but that's no problem

Was just thinking as I can get a complete engine and gearbox from a car/van for next to nothing

Either a Transit 2.5Di with a manual gearbox, or occasionally something like a Mercedes diesel with an auto box

Obviously mounting it is not an issue, and then would link it to the thrust bearing using a modified car propshaft, and then an adaptor to drive the boat prop/shaft

What about the clutch? Would it need the vehicle manual clutch connecting? Could do cable or hydraulic easily to a lever if needed

Just thought it would be an easy way for me to get a gearbox, it would have reverse and several forward speeds including an over drive ratio (so even if limited by hull speed, could drop into overdrive to drop rpm for fuel economy)

Reverse would be slow admittedly (most car/van boxes have a 2.5~3.5:1 ratio) but then would have a selection of forward speeds

Manual box would require linkages making to move the selector (unless already cable change) and the auto would have cable or electronic selection

But I'm not too worried about that side of it

What about the torque converter on an auto? Or the clutch plate on a manual?

Would they need modification?


Just an idea overall, I know boats arent cheap no matter what, but obviously modifications and custom mounts etc will cost me next to nothing

And it would save having to buy a marine gearbox and possibly making or buying an adaptor plate to mate with engine



Exhaust I have been weighing up options and have decided a dry stack heavily wrapped and then surrounded by a length of stainless flue would be fine for my purpose

I would ideally like to have little/no raw water being pumped around

I have been researching about 'keel' cooling as an option as well but haven't found any pictures of a setup on a boat, only discussions about it

It’s been done before , one of my dads mates used a Morris 1000 engine and box in a boat in the 70s . If I were you I’d use any modern ish diesel that you can buy a water cooled manifold for , I’d go for a marina gearbox as there is no clutch involved , depending on what hip engine you require there are always plenty of good used gearboxes around .
Only today I found a complete range 4 Perkins on eBay with gearbox , loom dash etc £4500.

I do out of interest have a marine Fischer panda generator that’s got a 4 cylinder Kubota engine with a water cooled manifold I want out the way , pm me of your interested , you could also put the sound shield in place , would make it very quiet .

 

[oldgit]

Chap I know fitted an ancient diesel and auto box lifted directly from an old london cab.
Went to great deal of time and bodgy trouble to get it installed in an old Seaworker.It was a work of art and Hammerite.
On its maiden voyage it managed to get whole yards before there was an almightly bang and the boat drifted back ashore in cloud of smoke.
Gearbox had broken.

 

[PCUK]

Chap I know fitted an ancient diesel and auto box lifted directly from an old london cab.
Went to great deal of time and bodgy trouble to get it installed in an old Seaworker.It was a work of art and Hammerite.
On its maiden voyage it managed to get whole yards before there was an almightly bang and the boat drifted back ashore in cloud of smoke.
Gearbox had broken.

If only he had had an outdrive!

 

[rotrax]

Tom Rolt, author of the canal book Narrow Boat which was published just after the war, had a Shropshire Union fly boat - a lightly built canal boat that worked 'Fly' - ie non stop, pulled by teams of horses with perishable goods and/or passengers.

It had been fitted before he got it with model T Ford engine and gearbox, the reduction made motorcycle style with chain and sprockets, gearbox output shaft to prop shaft. He subsequently converted it to run on paraffin after it had been started on petrol for use during the war when petrol was rationed.

Another idea - with toothed belts, perhaps a safer method?

 

[scottie]

If you ever come to sell your acceptable to you non standard ideas may prove a put off

 

[rotrax]

Plenty of car engined boats here in NZ.

My mate Errol has put a Ford Tractor engine in his steel 55 footer plus making up a drive train incorporating H/D CV joints.

As facilities are few and far between in NZ, he wanted easy access to the engine, including being able to get the sump off, so he mounted it high.

A really good vessel for NZ conditions, set up for singlehanding.

I dont believe dieselboatman has making a profit in mind, just getting a boat working at low cost, using his skills and experience.

 

[Assassin]

I agree, nothing wrong with trying something different.

 

[oldgit]

If only he had had an outdrive!

Think he did look at fitting an outdrive ?‍ but went for the more reliable option.
Happened at Kingsferry Boat Club on the Swale .( which is a Ria ! ) Most of the club was of course standing on the shore watching the event unfold .

When you perform the most amazing and perfect arrival under the most difficult circumstances possibly nobody will be around to see it.
When on the other hand you cock it up big time half the world will be there to watch and give you marks out of 10.
That poxy lock at Chatham MDL has caught me out several times.

 

[Rickard]

One thing that I´m guessing needs to be looked in to is that a gearbox from a car isn´t made for the force that the propeller causes to the outgoing shaft of the gear box

 

[dava]

Can I suggest a book by a bloke called Nigel Warren named marine conversions. It's absolutely genius. My dad done stacks of conversions on the Tyne during the 70s and 80s mainly on old BMC bread van engines based on this book.
The basic premise was to dismantle the gearbox and there was a way you could connect 2 shafts inside using 2 motorbike sprockets and a short chain. This put 3rd gear directly opposite reverse so you could still use a lever in the wheelhouse, maybe even a Morse although we were never that posh. You still need a clutch which to be honest I found handy as I was learning the ropes as you could slip the clutch and go really slow. In fact I remember when I first started I didn't have the weight to press the clutch on 1 boat and had to push myself down off the dash.
The only snag was if you were a bit keen on the revs in reverse the chain could snap as I done as an 11 year old once, after being made to strip it all down and fix it that never happened again haha