Engine replacement cost

[RichM]

A while ago I was looking to replace a working Barrus Shire 30hp engine with a Beta Marine 43hp with additional skin tanks and a larger prop. Both checked the access for engine removal and as I thought, access wasn't an issue. I was quoted in the region of £12k (including fitting) by two local boat yards. In the end we decided not to proceed. Not being an expert on this, do these quotes sound reasonable for what I asked for?

If I wish to pursue this again in future, is it usually more cost effective to go down the reconditioned route?

[RLWP]

It is usually cheaper to go down the reconditioned route as you don't run into the 'oh but that doesn't fit/suit/match the new engine' stuff

 

Not entirely sure about Barrus-Shire engines though

 

Why do you want to do this?

 

Richard

[MtB]

I'm guessing he wants the extra 13hp...

(An extra 42% power.)

[RichM]

The current Barrus Shire 30hp engine is fine for propelling my 55ft boat along a canal at 4mph, although it's a little on the noisy side at 2500rpm! The trouble comes when cruising rivers, particularly the Severn. I wouldn't mind having a more suitable engine in an ideal world. - though not at £12k!

[ditchcrawler]

Kings Lock at Middlewich use to do a deal on engine swaps that looked reasonable

[alan_fincher]

The current Barrus Shire 30hp engine is fine for propelling my 55ft boat along a canal at 4mph, although it's a little on the noisy side at 2500rpm! The trouble comes when cruising rivers, particularly the Severn. I wouldn't mind having a more suitable engine in an ideal world. - though not at £12k!

 

The 2,500 RPM to push the boat along on canals sounds distinctly wrong to me.

 

Are you sure the gearbox and prop are well matched to this engine, that the gearbox isn't slipping and that the prop is in good order wit no significant damage.

 

This is a narrow boat, isn't it, not a wide beam?

[Tony Brooks]

The current Barrus Shire 30hp engine is fine for propelling my 55ft boat along a canal at 4mph, although it's a little on the noisy side at 2500rpm! The trouble comes when cruising rivers, particularly the Severn. I wouldn't mind having a more suitable engine in an ideal world. - though not at £12k!

 

I suspect a prop change might need investigating. I have just brought a 54ft boat up the Severn with in on amber and a fair flow with a 3 pot Bukh (nominally 30+ BHP) at a maximum of 2000 rpm and mostly 1800 rpm Or less. The last stretch to Stourport yesterday morning at 1500 rpm,

 

I do not have my manual with me so can't check the power curves but at 1800 RPM it would have been developing less than 30bhp while yours at 2500 rpm would be much closer to 30 bhp.

 

Alan beat me to it, mine has a 2.5:1 reduction ratio.

Edited July 16, 2016 by Tony Brooks

[cuthound]

In 2013 we paid about £7,000 for ABC at Gayton to replace the BMC 1.8 with a Beta 43, so £12,000 seems a bit high even if the skin tank needs modifying.

[dor]

The current Barrus Shire 30hp engine is fine for propelling my 55ft boat along a canal at 4mph, although it's a little on the noisy side at 2500rpm! The trouble comes when cruising rivers, particularly the Severn. I wouldn't mind having a more suitable engine in an ideal world. - though not at £12k!

Definitely sounds under-propped to me. Canal boats should really be a little bit over-propped, so that you will not make maximum revs when in gear, but should get close to maximum on the power curve.

 

For information, my Vetus will rev to over 3000 rpm in neutral, but will only make about 2,600 in gear, and cruises normally at 1400 rpm which is about 3.5 mph. I would think this is pretty normal for a modern engine.

[Flyboy]

The current Barrus Shire 30hp engine is fine for propelling my 55ft boat along a canal at 4mph, although it's a little on the noisy side at 2500rpm! The trouble comes when cruising rivers, particularly the Severn. I wouldn't mind having a more suitable engine in an ideal world. - though not at £12k!

What size prop. & gear ratio have you got? It sounds seriously under propped to me.

[MtB]

The current Barrus Shire 30hp engine is fine for propelling my 55ft boat along a canal at 4mph, although it's a little on the noisy side at 2500rpm! The trouble comes when cruising rivers, particularly the Severn. I wouldn't mind having a more suitable engine in an ideal world. - though not at £12k!

 

 

This sounds very wrong to me too. How do you know it's doing 4mph at 2,500rpm? It might be 5mph, in which case dropping the revs to 1,500 will probably result in a fall in speed to about 4mph.

 

On a shallow canal the speed you achieve is not proportional to revs. Once you're hammering along, a big increase in engine speed adds hardly anything to the boat speed. Higher revs suck more water out from under the boat leading to the stern dropping ever lower and the boat having to climb the slope of water created at the front.

 

Or put another way, dropping the revs in shallow water causes very little loss of speed.

 

The reverse applied in deep water. If 2,500 really IS necessary in a shallow canal to get to 4mph, I'd predict 2,500rpm will result in 6 or 7mph in a deep river.

[Tony Brooks]

I think Mike might be onto the problem if the OP really does use 2500 rpm on canals to get to 4 mph. On narrow canals I can often get not much over 2.5 mph, adding more revs just makes the boat more difficult to handle and creates a larger wash.

 

If that 2500 rpm is on a canal and the tiller is easy to move and there is little wash then there is something amiss with the boat and its not an underpowered engine. If the tiller is difficult to move and a significant wash or draw of water is created then its driver error, just reduce the revs and accept you can never get to 4 mph on many canals today.

[RichM]

 

The 2,500 RPM to push the boat along on canals sounds distinctly wrong to me.

 

Are you sure the gearbox and prop are well matched to this engine, that the gearbox isn't slipping and that the prop is in good order wit no significant damage.

 

This is a narrow boat, isn't it, not a wide beam?

 

Yep that's correct, it's a narrowboat. The prop looked to be in good condition when inspected last October. Wasn't sure how to check for the gearbox slipping but I googled it and found the following:

 

"Signs include a high RPM (over 3,500), delays in acceleration, inability to reverse, unusual or burnt smells, the check engine light going off, difficulty shifting gears, shifting gears produces a harsh response, or any strange noises."

 

This was written in the context of a car so I'm not sure how relevant it is but It doesn't do any of this except for high RPM.

 

What size prop. & gear ratio have you got? It sounds seriously under propped to me.

 

The prop is 17 x 10 and the gearbox is a PRM 150D3.

 

 

 

This sounds very wrong to me too. How do you know it's doing 4mph at 2,500rpm? It might be 5mph, in which case dropping the revs to 1,500 will probably result in a fall in speed to about 4mph.

 

On a shallow canal the speed you achieve is not proportional to revs. Once you're hammering along, a big increase in engine speed adds hardly anything to the boat speed. Higher revs suck more water out from under the boat leading to the stern dropping ever lower and the boat having to climb the slope of water created at the front.

 

Or put another way, dropping the revs in shallow water causes very little loss of speed.

 

The reverse applied in deep water. If 2,500 really IS necessary in a shallow canal to get to 4mph, I'd predict 2,500rpm will result in 6 or 7mph in a deep river.

 

I checked the speed using GPS to get a rough idea. The ship canal is said to be 16ft deep in the centre and approx 100ft wide.

[RLWP]

 

 

PRM 150D3.

 

A three to one gearbox would explain the higher revs

 

Richard

[Tony Brooks]

Except my 2.5:1 only revs that high during an emergency stop. I know the OPs will rev a bit higher but not 700 rpm.

 

If the "ship canal" is the G&S then I went along it at 1300 to 1500 rpm at a good speed, faster than on narrow canals.

[David Mack]

The prop is 17 x 10 and the gearbox is a PRM 150D3.

 

A 10 in pitch appears to be rather fine to me.

[MtB]

 

The prop is 17 x 10 and the gearbox is a PRM 150D3.

 

 

Right, this is WAY too small.

 

Looking for a blade for a friend of mine with a BMC1500 and a 3:1 reduction box in their 57ft boat a while ago, I was chatting to Roger Preen at Calcutt.

 

I've just looked up my notes and Roger thought a 20"dia x 15" pitch blade would be about right. An extra 3" diameter and 50% bigger pitch!

[Jess--]

Without knowing the OP's boat I wonder if it an ex-hire one as they sometimes seem under-propped for their size.

 

I also remember hearing of a hire operator that had a preference for a particular type of old engine in their boats (details escape me) and that when selling off a boat they would pull the engine (to go into a new boat) and refit the cheapest new engine available (using the new engine as a means of increasing the boats value), I suspect that a barrus shire may fit into the cheapest available category.

[cuthound]

A three to one gearbox would explain the higher revs

 

Richard

Yes, DQ is a 60 foot boat with a Beta 43 driving through a PRM150 with 3:1 reduction. On deep is water, using the Ullysse speedometer app she does 2 mph at 100 rpm, 3 mph at 1500 rpm and 4 mph at 2000 rpm.

 

The other day I was on a friend's 58 foot boat, same engine and gearbox but with 2:1 reduction, so we checked the speed/rpm on that.

 

As expected 1000 rpm equalled 3 mph, 1500 rpm was 4 mph.

 

Much more relaxed cruising, due to the lower revs, but couldn't go slower than 2.7 mph (on tickover) past moored boats.

 

Horses for courses.

[MtB]

Yes, DQ is a 60 foot boat with a Beta 43 driving through a PRM150 with 3:1 reduction. On deep is water, using the Ullysse speedometer app she does 2 mph at 100 rpm, 3 mph at 1500 rpm and 4 mph at 2000 rpm.

 

The other day I was on a friend's 58 foot boat, same engine and gearbox but with 2:1 reduction, so we checked the speed/rpm on that.

 

As expected 1000 rpm equalled 3 mph, 1500 rpm was 4 mph.

 

Much more relaxed cruising, due to the lower revs, but couldn't go slower than 2.7 mph (on tickover) past moored boats.

 

Horses for courses.

 

 

If both boats had the correctly calculated propeller sizes, the results would have been the same. We may therefore conclude your boat is like the OP's, badly under propped.

[magnetman]

Without knowing the OP's boat I wonder if it an ex-hire one as they sometimes seem under-propped for their size.

 

I also remember hearing of a hire operator that had a preference for a particular type of old engine in their boats (details escape me) and that when selling off a boat they would pull the engine (to go into a new boat) and refit the cheapest new engine available (using the new engine as a means of increasing the boats value), I suspect that a barrus shire may fit into the cheapest available category.

Interesting observation on ex hire boats.

 

One of my boats was built as a hire boat and if does seem rather under propped.

 

Why would this be?

 

Slowing down hire boats? Saving fuel?

[Tony Brooks]

 

 

Right, this is WAY too small.

 

Looking for a blade for a friend of mine with a BMC1500 and a 3:1 reduction box in their 57ft boat a while ago, I was chatting to Roger Preen at Calcutt.

 

I've just looked up my notes and Roger thought a 20"dia x 15" pitch blade would be about right. An extra 3" diameter and 50% bigger pitch!

 

Just a warning. A 20" prop should not be fitted into a boat with a 20" stern post as many modern use. I think mine is 16x14 but I do not have the invoice to look it up.

Interesting observation on ex hire boats.

 

One of my boats was built as a hire boat and if does seem rather under propped.

 

Why would this be?

 

Slowing down hire boats? Saving fuel?

 

Slowing down the boat and to make sure the alternator turns fast enough for maximum charge at canal speed,

[magnetman]

 

Just a warning. A 20" prop should not be fitted into a boat with a 20" stern post as many modern use. I think mine is 16x14 but I do not have the invoice to look it up.

 

 

Slowing down the boat and to make sure the alternator turns fast enough for maximum charge at canal speed,

Thanks for that its interesting.

[cuthound]

If both boats had the correctly calculated propeller sizes, the results would have been the same. We may therefore conclude your boat is like the OP's, badly under propped.

How can the results be the same when one has a 3:1 reduction and the other a 2:1 reduction?

 

The speed over the water was identical, allowing for the different reduction ratios.

[MtB]

How can the results be the same when one has a 3:1 reduction and the other a 2:1 reduction?

 

The speed over the water was identical, allowing for the different reduction ratios.

 

 

That's a very big question that takes us into engine torque curves and optimium speeds for power delivery. It's all been analysed here in the past in 100 post threads. Will have a search later and see if I can find one.

 

But simply put, you're 'looking down the wrong end of the telescope'. The same engine with a 3:1 box needs a bigger diameter/longer pitch blade than the with a 2:1 box, in order to achieve the same engine revs for a given speed through the water, loosely speaking.