Fitting heat exchanger cooled engine into narrowboat

[Philip]

Thanks

[TheBiscuits]

1 hour ago, Philip said:

Just a point about the 20hp in my cruiser; under load the maximum I can get out of it is about 13hp because of the deficiency in the saildrive:engine ratio. I have gone upstream on the Severn twice with this engine in reasonable green conditions, and the most it could do at maximum revs was just about 3mph..the engine quickly overheated both times when pushed, at more normal revs it was doing about 2mph. 

 

Is your raw water cooling system in good condition?  Have you physically checked all hoses/filter(s)/pump/impeller/heat exchanger all the way through the system?  

 

As many others have said above, 3mph-ish upstream on the Severn is about right in normal conditions.  Don't forget you'll be travelling against a flow of 1-2mph, so you are actually doing 4-5 mph through the water but only 2-3 mph speed over ground.

 

 

Back to your original post about the narrowboat, it's a bit hard to judge the exact size of that skintank from the photo,  but it looks on the small side to me for your Beta 16 never mind the 20.  If the earlier guess of 3 sq ft is about right it's undersized for full power but will be fine on canals where you don't need full power.  

 

 

[Philip]

11 minutes ago, TheBiscuits said:

 

Is your raw water cooling system in good condition?  Have you physically checked all hoses/filter(s)/pump/impeller/heat exchanger all the way through the system?  

 

As many others have said above, 3mph-ish upstream on the Severn is about right in normal conditions.  Don't forget you'll be travelling against a flow of 1-2mph, so you are actually doing 4-5 mph through the water but only 2-3 mph speed over ground.

 

 

Back to your original post about the narrowboat, it's a bit hard to judge the exact size of that skintank from the photo,  but it looks on the small side to me for your Beta 16 never mind the 20.  If the earlier guess of 3 sq ft is about right it's undersized for full power but will be fine on canals where you don't need full power.  

 

 

 

Yes, change the impeller approx. once per year, heat exchanger isn't blocked and I regularly drain the strainer and give the raw water inlet a blast with hand pump to clear any debris around the inlet holes in the saildrive leg. The engine was built in 2017 so the hoses should be ok, they look in good nick anyway.

 

An Aintree engineer said that the 16hp and single skin tank set up might struggle a bit in situations when full power/higher revs are needed. Knowing where the skin tank is now, it looks like it would easy enough to weld one onto the port side of the swim...plenty of room there. There also looks to be enough room to put a fan in there to provide additional air cooling.

 

 

Edited December 30, 2020 by Philip

[TheBiscuits]

Just now, Philip said:

 

Yes, I've changed the impeller approx. once per year, heat exchanger isn't blocked and I regularly drain the strainer and give the raw water inlet a blast with hand pump to clear any debris around the inlet holes in the saildrive leg. The engine was built in 2017 so the hoses should be ok, they look in good nick anyway.

 

An Aintree engineer has suggested the 16hp and single skin tank might struggle a bit in situations when full power/higher revs are needed. Knowing where the skin tank is now, it looks like it would easy enough to weld one onto the port side of the swim...plenty of room there. There also looks to be enough room to put a fan in there to provide additional air cooling.

 

 

 

No worries - it's always worth asking if people have serviced the raw water system - many don't know they need to!  Just watch the hoses - if they start delaminating inside they can work fine at low speed and then lift a flap of the rubber liner at higher speed which blocks the flow when you need it most.  

 

With appropriately sized skin tanks you won't need a fan - the cooling is far more efficient through the outside of the hull into the water - it's not an air radiator like on a car, even though it will do a bit of that. 

 

It's also well worth taking the outside of the hull in the skin tank area right back to bare metal before re-blacking the boat.  If there is too much blacking on the outside it reduces the efficiency of the heat transfer as it's effectively insulated from the water.  

 

If the water in the skintank is a nasty red-brown rusty colour, thoroughly flush the entire system, getting rid of as much crap as you can.  A hosepipe and a wet and dry vac are useful for this ... 

 

If the antifreeze-water mixture is either not correctly mixed or is the wrong ratio it will not work as well as it should.  I'd use about 1 antifreeze to 2 water (a 33% mix) but it depends on the antifreeze.  It must be premixed before putting it in the system to prevent layering.

 

Apologies if I'm teaching you to suck eggs on any of this, but I'm guessing this is your first skintank cooled system.

[Philip]

32 minutes ago, TheBiscuits said:

 

No worries - it's always worth asking if people have serviced the raw water system - many don't know they need to!  Just watch the hoses - if they start delaminating inside they can work fine at low speed and then lift a flap of the rubber liner at higher speed which blocks the flow when you need it most.  

 

With appropriately sized skin tanks you won't need a fan - the cooling is far more efficient through the outside of the hull into the water - it's not an air radiator like on a car, even though it will do a bit of that. 

 

It's also well worth taking the outside of the hull in the skin tank area right back to bare metal before re-blacking the boat.  If there is too much blacking on the outside it reduces the efficiency of the heat transfer as it's effectively insulated from the water.  

 

If the water in the skintank is a nasty red-brown rusty colour, thoroughly flush the entire system, getting rid of as much crap as you can.  A hosepipe and a wet and dry vac are useful for this ... 

 

If the antifreeze-water mixture is either not correctly mixed or is the wrong ratio it will not work as well as it should.  I'd use about 1 antifreeze to 2 water (a 33% mix) but it depends on the antifreeze.  It must be premixed before putting it in the system to prevent layering.

 

Apologies if I'm teaching you to suck eggs on any of this, but I'm guessing this is your first skintank cooled system.

No worries and thanks for the info - useful to know particularly regarding the re-blacking in the skin tank area (and potentially on the other side of the swim!). Yes, this is the first boat I've owned which uses the skin tank cooling; my cruiser has always been raw water cooled, initially directly with the old Volvo Penta and then via heat exchanger with the Kubota.

 

I think one of the first things to do (after blacking and engine service) when I take hold of my narrowboat is to weld in the second skin tank with the baffle inside, perhaps go for 5sq feet as per Beta Marine guidelines if I do decide to fit the 20hp engine in it after trials. I realise this would render my cruiser little more than scrap value, but perhaps the 16hp which is taken out of the narrowboat could go in my cruiser before putting it on the market...or see if an outboard could be fitted to it.

Edited December 30, 2020 by Philip

[TheBiscuits]

1 minute ago, Philip said:

I think one of the first things to do (after blacking and engine service) when I take hold of my narrowboat is to weld the second skin tank on with the baffle inside, perhaps go for 5sq feet as per Beta Marine guidelines if I do decide to fit the 20hp engine in it. I realise this will render my cruiser little more than scrap value, but perhaps the 16hp which is taken out of the narrowboat could go in my cruiser before putting it on the market...or see if an outboard could be fitted to it.

 

I'd do the welding before the blacking, if only to save having to do the blacking twice ...

 

If you are lucky the 16 and the 20 might be swappable without too much fuss, and if you are doing this then obviously while the engine is out makes doing the skin tank a lot easier. 

 

If it doesn't quite work that way there are techniques for building a skin tank from the outside  - either using the hull as the inside of the tank and building the tank outwards, or cutting away the hull and fabricating the tank inside out then reattaching the outer hull section.  Whichever way, make sure to pressure test the tank before dropping it back in the water

 

[Tony Brooks]

The  insulation looks needlessly complicated to me if it really does have a raw water pump with a rubber impeller. I think that I can see an engine water pump (that is different to the raw water pump) will happily push water through the skin tank. If the raw water system has been piped to the skin tank and then that water is passed through the heat exchanger to cool the engine yo have two coolant systems when one will do. modifying to simplify the cooling system will not do anything to solve an undersized skin tank but it does away with the raw water pump that needs regular impeller changes and its own drive system.

 

If this were mine I would remove the heat exchanger core, cap the two raw water connections on the manifold/heat exchanger, remove the raw water pump and then connect the skin tank outlet to the ENGINE water pump inlet and the large port on the manifold/heat exchanger to the skin tank inlet.

 

I can't be sure this is not how that engine has been piped because I can't see the raw water pump (if it has one) or the front of the engine but the simpler thee system the less there is to go wrong so the better I feel

[TheBiscuits]

Two different engines Tony.  The photo is only of the skintank cooled Beta 16

[Tony Brooks]

7 minutes ago, TheBiscuits said:

Two different engines Tony.  The photo is only of the skintank cooled Beta 16

I am confused as to what boat/engine is being discussed. But if either engine has a raw water pump plus skin tank my opinion stands for that engine.

[TheBiscuits]

7 minutes ago, Tony Brooks said:

I am confused as to what boat/engine is being discussed. But if either engine has a raw water pump plus skin tank my opinion stands for that engine.

 

He was originally thinking of swapping the raw water cooled Beta 20 from the cruiser into the narrowboat, and using the skintank and the raw water together. 

 

He now is thinking of making a new, correctly sized skintank in the narrowboat, and hopefully swapping the engines over if the parts are interchangeable between the Beta 20 and the Beta 16.  I think he's scrapped the idea of having both a skintank and a raw water cooling system together because of this thread, which makes sense to me.

 

 

[Tony Brooks]

4 minutes ago, TheBiscuits said:

 

He was originally thinking of swapping the raw water cooled Beta 20 from the cruiser into the narrowboat, and using the skintank and the raw water together. 

 

He now is thinking of making a new, correctly sized skintank in the narrowboat, and hopefully swapping the engines over if the parts are interchangeable between the Beta 20 and the Beta 16.  I think he's scrapped the idea of having both a skintank and a raw water cooling system together because of this thread, which makes sense to me.

 

 

 

so he can still convert a raw water Beta 20 to tank cooling much as I said. I agree running both systems would be a poor idea.

[Philip]

Just to give a comparison, here are 2 photos of the 20hp engine currently in my cruiser with the raw water pump gubbins, just after it was installed.

[TheBiscuits]

Ooh shiny!

 

I can see why you'd want to keep that one if it fits

 

 

[Philip]

15 minutes ago, TheBiscuits said:

 

He was originally thinking of swapping the raw water cooled Beta 20 from the cruiser into the narrowboat, and using the skintank and the raw water together. 

 

He now is thinking of making a new, correctly sized skintank in the narrowboat, and hopefully swapping the engines over if the parts are interchangeable between the Beta 20 and the Beta 16.  I think he's scrapped the idea of having both a skintank and a raw water cooling system together because of this thread, which makes sense to me.

 

 

Thanks - that is my thinking!

[Philip]

7 minutes ago, TheBiscuits said:

Ooh shiny!

 

I can see why you'd want to keep that one if it fits

 

 

Well...not quite as shiny now after a good few oil changes and 1500 running hours, but yes it's been excellent and I've serviced it going by the Beta recommended frequencies - so I'm hopeful it's still in good condition!

[J R ALSOP]

Not a big fan of that gas locker!

[Alan de Enfield]

10 minutes ago, J R ALSOP said:

Not a big fan of that gas locker!

 

When you look at how many boat gas explosions there are on 'lumpy water' and compare them to waters where a BSS is required, you can see why gas-lockers (on lumpy water) are treated the way they are.

Edited December 30, 2020 by Alan de Enfield

[OldGoat]

At the risk of being rubbished -

 

You ned to do more than just disconnect the freshwater coolant pump.

There's a heat exchanger built into the exhaust manifold box that may not be suitable for the temperatures of the exhaust gasses.

Indeed a live exhaust manifold is needed plus a silencer.

[Philip]

24 minutes ago, J R ALSOP said:

Not a big fan of that gas locker!

Was installed 8 years ago and has done its job and still in as good condition as when new. (and passed two BSS!) A seat covers the top of it normally.

Edited December 30, 2020 by Philip

[Philip]

12 minutes ago, OldGoat said:

At the risk of being rubbished -

 

You ned to do more than just disconnect the freshwater coolant pump.

There's a heat exchanger built into the exhaust manifold box that may not be suitable for the temperatures of the exhaust gasses.

Indeed a live exhaust manifold is needed plus a silencer.

Thanks, can do that remotely after taking the engine out of my cruiser.

[TheBiscuits]

37 minutes ago, J R ALSOP said:

Not a big fan of that gas locker!

 

Can you state your objections more clearly?  Do you (wrongly!) think it isn't BSS compliant, or do you just not like the appearance of plywood and think it needs painting?

 

 

Edited December 30, 2020 by TheBiscuits
clarity

[TheBiscuits]

17 minutes ago, OldGoat said:

At the risk of being rubbished -

 

You ned to do more than just disconnect the freshwater coolant pump.

There's a heat exchanger built into the exhaust manifold box that may not be suitable for the temperatures of the exhaust gasses.

Indeed a live exhaust manifold is needed plus a silencer.

 

I think Tony was a bit confused earlier.

 

Does anyone know if the marinisation bits are swappable between a Beta 20 Seagoing and a Beta 16 Greenline?  I don't know either way.  

 

Actually, just ringing or emailing Beta would answer this question - they are very good!

 

01452 723492 / sales@betamarine.co.uk

 

[Philip]

15 minutes ago, TheBiscuits said:

 

I think Tony was a bit confused earlier.

 

Does anyone know if the marinisation bits are swappable between a Beta 20 Seagoing and a Beta 16 Greenline?  I don't know either way.  

 

Actually, just ringing or emailing Beta would answer this question - they are very good!

 

01452 723492 / sales@betamarine.co.uk

 

Thanks, sent them an email.

 

Possibly another issue is that this Beta 20 currently has saildrive transmission with adapted plate, whereas the 16 engine has PRM 90 gearbox transmission. I've asked them about this.

[TheBiscuits]

Just now, Philip said:

Possibly another issue is that this Beta 20 currently has saildrive transmission with adapted plate, whereas the 16 engine has PRM 90 gearbox transmission. I've asked them about this.

 

If the boltholes and the shaft is in the same position, you are laughing, just swap the engine block.  Like I said, I don't know either way -  I have never played with the little Betas.

 

If there are enough differences, I'd say either source an alternate engine for the narrowboat or just live with the 16 - you haven't stress tested it yet AFAIK and it might be fine.  There are a lot of 25' boats with a 9.9 hp outboard and a 6" propeller, so a Beta 16 driving a 12" x 8" prop through a PRM 90 gearbox might be fine for the hull.

[Tony Brooks]

46 minutes ago, TheBiscuits said:

 

I think Tony was a bit confused earlier.

 

Does anyone know if the marinisation bits are swappable between a Beta 20 Seagoing and a Beta 16 Greenline?  I don't know either way.  

 

Actually, just ringing or emailing Beta would answer this question - they are very good!

 

01452 723492 / sales@betamarine.co.uk

 

Not confused, I never said anything about swapping parts, just remob=ving parts but the OP will have to fit a dry exhaust on the 20HP.

 

1 hour ago, OldGoat said:

At the risk of being rubbished -

 

You ned to do more than just disconnect the freshwater coolant pump.

There's a heat exchanger built into the exhaust manifold box that may not be suitable for the temperatures of the exhaust gasses.

Indeed a live exhaust manifold is needed plus a silencer.

As the way I described kept the manifold full of circulating coolant but without the heat exchanger core - so exactly like an indirect raw water cooled engine in  respect of the coolant against the hot parts of the manifold I don't see your point. I would see the point if it were an aluminium manifold and the suggestion was to run it dry. Yes a silencer will be needed but he probably has one plus the exhaust from his tank cooled dry exhaust engine.