New Engine - Bitten the Bullet

[WayneS]

Today we handed over the deposit on a new Beta 20Hp engine to replace the ever failing piece of junk that pretends to work (20year old Faryman 12Hp).

This has raised a few questions and I wonder if you folks could comment:

Engine Bearers.
We will not be able to use the existing setup which is a GRP plate that the current engine sits on. I intend to remove all of this plate and glass in two hardwood bearers directly onto the hull (GRP). Then use 8 coach-bolts to secure the mounts down onto the bearers. Am I on the right track. Alignment is not a problem for me as we are maintaining our Hydraulic drive system.

Fuel Return
Currently I only have a single pipe from the tank. The new Engine has a return way. Do I need to take this return back to the tank or can it simply T into the feed pipe before the pump?

Raw water pipe.
I was speaking to a guy a few weeks ago who suggested that we use fuel hose for the raw water feed. He has done this so that in the event of a fire, the engine should still get cooling water. Any comment?

Prop.
We currently have a 2-blade folder. We are thinking of just fitting a std 3 blade. Does it make a huge difference under sail. Are we talking knots or fractions of knots.

I’m sure that there will be loads more Q’s as we progress but that’s a start.

Regards

Wayne


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[billmacfarlane]

Does the prop shaft on the old engine revolve in the same direction as the new ?

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[WayneS]

I am assuming that you are referring to the direction on the back of the gearbox. We will not have a gearbox as the Hydraulic pump drives directly off the flywheel.

I have been told that the engine will drive my series2 Hydraulic pump OK so I have to assume that the crank/flywheel rotate in the correct direction.

As for prop-shaft rotation, it is immaterial. The hydraulics drive the same speed in both directions.

Cheers

Wayne


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[roger]

Bearers. Beta make at least two sorts of feet; normal and "atomic" for the same price and others to your needs at extra cost so you can choose. I suggest you get advice from them.
Propellor. Usually hydraulic drives are inefficient soaking up a lot of the available power so ordinary calculations may not work. You could reasonably expect to need a larger or higher pitched prop to use the extra power you are getting. Beta recommended me an unsuitable prop because (I'm told) thats what they buy in bulk. I had to reduce the pitch to make the engine reach a speed closer to maximum revs..
Fuel return. I believe you need the fuel return. The returned fuel is hot and needs to cool down in the tank.
Raw water pipe. The raw water intake is very close to the flywheel. Make sure it cant rub and wear through.
Prop type. We found a reduction in light airs performance with a 2 and with a three bladed fixed prop but the effect is likely to vary with your boat type. An efficient easily driven boat will suffer the greatest loss.
I fitted a speed seal to the raw water pump. It is very easy to lose those tiny screws if you change an impeller in a sea way.
We fitted a Beta 20hp in 2002 and very much like it. E-mail me if you want more opinions

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[tristan]

Fuel return will definately have to go back to the tank - it will cause problems guaranteed if you tee it ( the beta should come with an installation manual to give the information).

Coach screws into the wood will be ok to hold down the flexible mounts but not the solid engine feet (compression will occur otherwise) - remember to glass over the bearers completely otherwise any fuel, oil or water leak will rot the bearers over a period of time.

Fuel hose is ok for the water intake, but may suffer from internal delamination over years, we use exhaust hose as it is wire bound high temp rubber - you have to use better clamps (normal hose clips are not man enough) though.

Hope this helps, good luck with the installation.

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[pampas]

I have found by experience that if the system is gravity fed you will not find much difference to the overaul running if you tee into the feed line, but if pressure fed a slight reduction in injector noise is noticed, due I presume to the back pressure of the pump (Electric feed pump). I have not been able to detect any other adverse effects, Hope this info is of use.

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[WayneS]

Thanks for the input everybody. Very Useful

Regards

Wayne


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[Aeolus_IV]

Our fuel return is T's into the fuel line back at the tank end as we have a bag rather than a tank, and no fitting to put return into the bag. This then allows the returned fuel to go back through the whole length of the supply pipe, primary and secondary filters before beign used again - so there should be no problems. Certainly we've had none so far, when we get a proper fuel tank then the return can go into that properly.

We use fuel grade pipes for all cooling pipework - it was put to me that if there was a fire the last thing you needed was a cooling pipe burning through and leave a hole into the boat for the water to come in.

Changing from a 2-blade folding to a 3 blade wixed will have a noticable impact on sailing speed. We went from a 2-blad fixed to a 2-blade folding and gained probably a knot in medium/light airs. But as has been said, this will depend on how "slippery" your boat is under sail.

Jeff.

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[colvic]

I don't know your particular engine, but being fairly small is it three cylinder? If so, get the best feet/dampers that you can as there is more vibration with 3 cylinders than 4 or 2.

As regards the coach bolts, our mechanic tried that on our engine replacement, but in the end we had new bearers made so that the mountings lined up with the original holes in the steel plated which is bonded to the bearers. I appreciate that with a hydraulic drive stress on the engine mounts will be less than with a direct shaft drive, but better safe than sorry.

Is hydraulic drive good?


Phil

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[chrisD]

Any other views on relative vibration from three cylinders? I'm looking at up-dating from a Volvo MD11C (2 cylinders) to a 2030 (3 cylinders), or maybe the 3 cylinder Beta, and the dealers all reckon 3 cylinders should be smoother.

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[Aeolus_IV]

Replaced a MD2B with 3GM30F - reduction in shaking, vibration and noise is amazing. There does seem to be no substitute for numbers of cylinders to make for a smoother engine and all the benefits this brings.

Jeff.

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