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Callum4878

Beta marine engines

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Looking at a boat with a Beta 38hp engine, most boats I’ve looked with Beta engines have the 43hp engine, apart from the obvious 5hp, are there any other differences/problems? I’m new to boating.

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5 minutes ago, Callum4878 said:

Looking at a boat with a Beta 38hp engine, most boats I’ve looked with Beta engines have the 43hp engine, apart from the obvious 5hp, are there any other differences/problems? I’m new to boating.

No not realy. Just as good and in fact more than capable enough for any length narrowboat. Still 4 pot and iirc still kubota based.

Edit to add I have owned both versions.

Edited by mrsmelly

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My 62ft boat has a 35hp Beta, which might be considered a little underpowered, but has been fine most of the time. Had the temperature warning buzz a couple of times pushing fairly strong upstream currents, but I'm pretty sure this is down to the undersized skin tank, not the engine. 

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Only reason for asking really was that the Ribble link is on our agenda, and I understand a bit of oomph is required.

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22 minutes ago, Callum4878 said:

Looking at a boat with a Beta 38hp engine, most boats I’ve looked with Beta engines have the 43hp engine, apart from the obvious 5hp, are there any other differences/problems? I’m new to boating.

The difference in maximum power output is not significant as you will probably never want to use the extra 8hp (the 38 is in fact 35bhp if you read the small print!). Where there is a bit of a relevant difference is in the low rpm torque. The 38 is a smaller capacity engine (1500cc vs 2000cc) but achieves nearly the same power as the 43 at high rpm. But at idle, or just off idle, there is quite a lot less power. At 900rpm (just above idle of 850) there is roughly 6bhp available on the 38 vs 9bhp on the 43 (ie the 43 has 50% more).

Why is this relevant? It is to do with the loading of the accessories in particular the alternators. At 900 rpm the alternators are geared so they can produce pretty much their maximum output. But a big alternator  working hard puts a big mechanical load on the engine. And this is why the Beta 43 comes with a 175A alternator, whereas the 38 only has a 100A alternator. If you put a 175A alternator on a 38 and loaded it up, it would probably stall the engine or at least the engine would struggle to accelerate above idle with a bit of additional load from the propeller.

 

So it depends on whether you want a high power alternator or not!

5 minutes ago, Callum4878 said:

Only reason for asking really was that the Ribble link is on our agenda, and I understand a bit of oomph is required.

It will be more about the skin tank cooling capability than the sheer engine power. Many narrowboats are inadequately cooled and there is no point in having lots of power if you can't use it without the engine boiling over! The fastest I've ever wanted to run our 43 steadily was 2200 rpm and that was on the tidal trent. At that rpm it can produce about 28bhp. That was fast enough and I think if I had taken the revs right up to 2800 it would only have made more noise and vibration, probably wouldn't have made the boat go any faster.

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As it’s a completed new boat I’m looking at, I wouldn’t have the choice, but from what you’ve all said I’m not put off by the smaller motor and alternator.

Thanks all.

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16 minutes ago, Callum4878 said:

Only reason for asking really was that the Ribble link is on our agenda, and I understand a bit of oomph is required.

Don't over think it.  We have a Beta 35, which is actually rated at a max of 37.5BHP, so basically the same power as the Beta 38 which replaced it.  I think the Beta 38 may develop max power at a slightly lower RPM, but it is all at a much higher RPM than you are going to use on a narrowboat for any sustained period.  So the amount of power that the engine is developing at even fast river cruising RPM is much less and perfectly enough.  A well designed cooling system is much more important than the few extra BHP in my opinion.

 

We did the Ribble link last summer and it was absolutely fine, unless you always want to be that person the puts the hammer down and shoots off into the lead, only to be caught up by the other boats including us while he was hovering in the Douglas waiting for the tide to make a level with the Rufford branch, at which time they opened both ends of the lock and all 6 boats went straight through.

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19 minutes ago, nicknorman said:

The difference in maximum power output is not significant as you will probably never want to use the extra 8hp (the 38 is in fact 35bhp if you read the small print!). Where there is a bit of a relevant difference is in the low rpm torque. The 38 is a smaller capacity engine (1500cc vs 2000cc) but achieves nearly the same power as the 43 at high rpm. But at idle, or just off idle, there is quite a lot less power. At 900rpm (just above idle of 850) there is roughly 6bhp available on the 38 vs 9bhp on the 43 (ie the 43 has 50% more).

Why is this relevant? It is to do with the loading of the accessories in particular the alternators. At 900 rpm the alternators are geared so they can produce pretty much their maximum output. But a big alternator  working hard puts a big mechanical load on the engine. And this is why the Beta 43 comes with a 175A alternator, whereas the 38 only has a 100A alternator. If you put a 175A alternator on a 38 and loaded it up, it would probably stall the engine or at least the engine would struggle to accelerate above idle with a bit of additional load from the propeller.

 

So it depends on whether you want a high power alternator or not!

It will be more about the skin tank cooling capability than the sheer engine power. Many narrowboats are inadequately cooled and there is no point in having lots of power if you can't use it without the engine boiling over! The fastest I've ever wanted to run our 43 steadily was 2200 rpm and that was on the tidal trent. At that rpm it can produce about 28bhp. That was fast enough and I think if I had taken the revs right up to 2800 it would only have made more noise and vibration, probably wouldn't have made the boat go any faster.

Thnking about it, it may be the case that the Beta 35 actually has a max power of slightly more than the Beta 38, but not relevant as it is all above 3000 PRM, which you will not get near.  On the Ribble link as with other big rivers I cruised at 2000RPM, and I think at that the Beta 35 develops about 25BHP, so sounds like really not that different to the Beta 43 in terms of raw power.  One thing I did do though to be cautious on the way up the Ribble Link where you are straight out onto the tidal part, pushing the tide, was to run the engine for an hour before we set off, so that the bulk of the battery charging was done by then.

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I have a Beta 38 in my boat, and fully agree with both @nicknorman and @john6767 (which might be a first! :))

 

Peak power is at 2800 rpm as Nick says, but the only time you want to be approaching those revs is in an emergency - probably when towing another boat off a weir!  Brisk uphill cruising on the Severn above Gloucester last year I was maybe doing 2000-2100.  I think I redlined it once in 5 years to see if it would - not quite as it's very slightly overpropped.

 

There are lots of boats with a hell of a lot less oomph than a Beta 38 have done the Ribble crossing with no problems.

 

 

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We have a beta 38 fitted with a travelpower in our 19 year old 60ft boat and not had any issues so far, mind you we've not done any cruising against a significant flow yet but I suspect the previous owners have given the amount of "river" books left onboard. 

 

Like others have said I suspect the cooling system will be the limiting factor rather than the engine power.

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48 minutes ago, Callum4878 said:

Only reason for asking really was that the Ribble link is on our agenda, and I understand a bit of oomph is required.

49 minutes ago, Callum4878 said:

As it’s a completed new boat I’m looking at, I wouldn’t have the choice, but from what you’ve all said I’m not put off by the smaller motor and alternator.

Thanks all.

My boat is 57' and was new. It was originally specified with a Beta Marine 38 and I asked for a 43 to be installed instead, mainly for the odd occasion when we would be on a river. Unfortunately my request to upgrade the engine didn't make it to the factory floor (but the accounts department knew and invoiced accordingly). There was no problem getting the builder to accept they had made a mistake and retrofit the 43, but for various reasons (some of them my choice) it did take about 9 months before it could be done.

 

Once the 43 was fitted and I could compare it to the 38 the difference it made to the handling of the boat was, to me, a significant improvement. I had thought hard about paying for the larger engine and if I hadn't had and used the 38 I think at the back of my mind I would always have wondered if spending the extra money was worthwhile. Having had experience of both engines I am pleased I upgraded to the 43.

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If the boat in question was still in build, I must admit that I’d probably go for the upgrade, as I’ve always been a biker, currently having a 1400cc 110bhp bike.

But I must get those thoughts out of my head now I’m going to be a boater.

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14 minutes ago, BrumSaint said:

My boat is 57' and was new. It was originally specified with a Beta Marine 38 and I asked for a 43 to be installed instead, mainly for the odd occasion when we would be on a river. Unfortunately my request to upgrade the engine didn't make it to the factory floor (but the accounts department knew and invoiced accordingly). There was no problem getting the builder to accept they had made a mistake and retrofit the 43, but for various reasons (some of them my choice) it did take about 9 months before it could be done.

 

Once the 43 was fitted and I could compare it to the 38 the difference it made to the handling of the boat was, to me, a significant improvement. I had thought hard about paying for the larger engine and if I hadn't had and used the 38 I think at the back of my mind I would always have wondered if spending the extra money was worthwhile. Having had experience of both engines I am pleased I upgraded to the 43.

 

Did they also uprate the propeller when they swapped the engines?

 

If they went with standard sizing, they might have swapped a 17" x 10" for an 18" x 12", and I would expect that to make a lot more difference than just swapping the engine block and keeping the same prop.

 

Add a bit:

 

Even worse, they could have fitted the 18" x 12" to the Beta 38, in which case it would always have been struggling with it.

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52 minutes ago, TheBiscuits said:

I have a Beta 38 in my boat, and fully agree with both @nicknorman and @john6767 (which might be a first! :))

 

Peak power is at 2800 rpm as Nick says, but the only time you want to be approaching those revs is in an emergency - probably when towing another boat off a weir!  Brisk uphill cruising on the Severn above Gloucester last year I was maybe doing 2000-2100.  I think I redlined it once in 5 years to see if it would - not quite as it's very slightly overpropped.

 

There are lots of boats with a hell of a lot less oomph than a Beta 38 have done the Ribble crossing with no problems.

 

 

In both directions, we had a older narrowboat with a 2 cyl lister under the cruiser stern.  One of the boat yard guys that operate Tarleton  lock told me that he thought they should be banned as they were basically the boat they had the most trouble with.  Both made it across, but not without some drama.

 

The one on the way up was initially kicking a ton of smoke out as I left him standing on the Douglas, and as he slowed to stop on the pontoon in Savick Brook the engine stopped and would not restart until it cooled at bit.  The one the other way, I did not notice a lot of smoke, and it made good speed down the Ribble, but as he hovered on the Douglas waiting for the lock his engine stopped and again would not restart, and he had to resort to his backup outboard.  
 

I guess I am saying that you would probably be surprised with the boats that do this, and to worry about if a Beta 38 is going to be better than a Beta 43, is orders of magnitude down compared to just having a basically reliable well coolEd engine.

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29 minutes ago, TheBiscuits said:

 

Did they also uprate the propeller when they swapped the engines?

 

If they went with standard sizing, they might have swapped a 17" x 10" for an 18" x 12", and I would expect that to make a lot more difference than just swapping the engine block and keeping the same prop.

 

Add a bit:

 

Even worse, they could have fitted the 18" x 12" to the Beta 38, in which case it would always have been struggling with it.

The current prop is 18"x12" as recommended by Beta for a 43, (Incidentally Beta recommend a 16"x 8" for the 38). I don't know if it was changed, but the owner's manual, which has the orginal 38 listed does list the propeller as 18"x12". So you may be right and it struggled because of the propeller, all I know is that once the 43 was fitted the handling of the boat, not just the power, improved. 

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6 minutes ago, BrumSaint said:

The current prop is 18"x12" as recommended by Beta for a 43, (Incidentally Beta recommend a 16"x 8" for the 38).

 

17" x 10" for inland use

https://betamarine.co.uk/inland-propellers/ 

 

16" x 8" for seagoing boats.

https://betamarine.co.uk/seagoing-propellers/

 

7 minutes ago, BrumSaint said:

I don't know if it was changed, but the owner's manual, which has the orginal 38 listed does list the propeller as 18"x12". So you may be right and it struggled because of the propeller, all I know is that once the 43 was fitted the handling of the boat, not just the power, improved. 

 

Yep, that'll have done it!  

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2 hours ago, Callum4878 said:

Looking at a boat with a Beta 38hp engine, most boats I’ve looked with Beta engines have the 43hp engine, apart from the obvious 5hp, are there any other differences/problems? I’m new to boating.

Not much both are kubota based and good engines.  I have one on our 50ft boat.  It seems on 57ft+ length boats many have been fitted with the Beta 43 in more recent years but there seems to be a fashion for fitting more powerful engines these days.  The power of the Beta38 is just fine on both canal and rivers in my experience.  I have had no issues servicing or any particular mechanical problems.

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1 hour ago, TheBiscuits said:

 

Did they also uprate the propeller when they swapped the engines?

 

If they went with standard sizing, they might have swapped a 17" x 10" for an 18" x 12", and I would expect that to make a lot more difference than just swapping the engine block and keeping the same prop.

 

Add a bit:

 

Even worse, they could have fitted the 18" x 12" to the Beta 38, in which case it would always have been struggling with it.

Up to last year I have never known the prop size on our boat with a Beta 38  (or rather 35 as it is an old engine and has just one Alternator it's red rather than green and 1995 vintage) other than measuring as best I could one blade it came out as 18"  I used a drydock for a couple of weeks last July to do blacking and painting.  So I had a look to see if it had any marks. It was stamped  18X13 and certainly by tape measure has an 18" diameter.

 

It should be rather too big but I have never had an issue and it trucks along well on Canals and Rivers.  I can't say if it is able to reach max RPM as I do not have a Tacho to measure that but I suspect that the prop probably does limit the upper rev range.  Fuel consumption is fine too.

Edited by churchward

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4 minutes ago, churchward said:

Up to last year I have never known the prop on our boat with a Beta 38  (or rather 35 as it is an old engine and has just one Alternator it's red rather than green and 1995 vintage) I used a drydock for a couple of weeks to do blacking and painting.  So I had a look to see if it had any marks. It was stamped  18X13 and certainly by tape measure has an 18" diameter.

 

It should be rather too big but I have never had an issue and it trucks along well on Canals and Rivers.  I can't say if it is able to reach max RPM as I do not have a Tacho to measure that but I suspect that the prop probably does limit the upper rev range.  Fuel consumption is fine too.

 

Yeah, it is always more art than science, but there's a lot of science in prop selection too!  It certainly sounds like you are overpropped and won't be able to get maximum theoretical power out of your engine, but it doesn't really matter on the canals and rivers unless you are doing something very unusual. 

 

The old joke is that it's one horsepower for going forwards and the rest of the horses for stopping, which while not exactly true isn't completely wrong either.   Narrowboats are basically floating skips anyway, so most of the fine points of balancing hull design and propeller go out of the window, and any prop that can't survive hitting a shopping trolley is useless on the canals.

 

 

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2 hours ago, TheBiscuits said:

 

17" x 10" for inland use

https://betamarine.co.uk/inland-propellers/ 

 

16" x 8" for seagoing boats.

https://betamarine.co.uk/seagoing-propellers/

 

 

16.5 x 11 is perfect on our 38, we get within spitting distance of the full 3000 RPM under load.  The only time it's been to full speed has been going uphill through a bridge hole in flood, and on open water to see what happens (a huge amount of wash and not much extra speed).

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4 hours ago, waterdog said:

Like others have said I suspect the cooling system will be the limiting factor rather than the engine power.

Indeed and if things are getting too hot send someone into the shower or turn on the washing machine (if it has a hot feed)!  :)

Edited by robtheplod

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3 minutes ago, robtheplod said:

Indeed and if things are getting too hot send someone into the shower or turn on the washing machine (if it has a hot feed)!  :)

 

It's quite difficult to do that on a big river singlehanded though ...

 

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3 hours ago, TheBiscuits said:

 

Did they also uprate the propeller when they swapped the engines?

 

If they went with standard sizing, they might have swapped a 17" x 10" for an 18" x 12", and I would expect that to make a lot more difference than just swapping the engine block and keeping the same prop.

 

Add a bit:

 

Even worse, they could have fitted the 18" x 12" to the Beta 38, in which case it would always have been struggling with it.

 

My 60 foot narrowboat has a Beta 43 and was initially fitted with a 17" x 11" prop. This meant normal canal cruising speed was 1500rpm (relatively noisy) and the boat was a nightmare to stop in a hurry.

 

Last year I changed it for an 18" x 12" and it has made a huge difference. Canal cruising is much more relaxed at 1250 rpm and the boat stops in a much shorter distance without the stern paddling across the canal.

 

Fuel consumption is reduced as well. What's not to like. 😁

Edited by cuthound
To add the last paragraph
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6 minutes ago, Onewheeler said:

16.5 x 11 is perfect on our 38, we get within spitting distance of the full 3000 RPM under load.  The only time it's been to full speed has been going uphill through a bridge hole in flood, and on open water to see what happens (a huge amount of wash and not much extra speed).

 

I tried it on mine (17" x 11") to see then looked at the fuel curve for the engine!

 

It uses 6 times as much juice at full chat compared to normal cruising revs.  Plus the centreline-moored boaters get very cross. :D

 

 

 

 

 

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