Twin engines

[lilianroyle]

I am in the process of making the transition from sail to motor. I’m looking at 70’s TSDY’s
A couple of things. I find the idea of not having a sail a bit unnerving. What to do if the engines stop working? I assume it would be very unusual for both engines to fail, why might that happen? I saw a couple of photos of Silver type boats with auxiliary steadying sail. Do motors boats of the channel crossing type ever jury rig sails?
Secondly I’m looking for something that would be reasonably seaworthy but suited also for European rivers and canals. Given the speed limits on the canals would it be best for the engines to be run just 1 at a time at higher revs or both at lower.
Thanks in advance for your thoughts

 

[Greg2]

With well maintained diesels the most likely cause of a breakdown will be bad fuel so good filtration and looking after the tanks with regular dosing with an additive will help in that regard. Note that the biocide type kill bug but leave debris and the enzyme type also kill bug but also help water and debris get burnt by the engines.

Having twins helps with manoeuvrability and it is a preference amongst U.K. motor boaters with the perceived benefit of redundancy. Reality is that single engines are likely to be fine if the fuel is looked after.

Running on one engine inland is a thing (we do it) but you need to be sure that your gearbox type allows it in terms of sufficient lubrication because the shaft will keep turning (some require the engine to be running to provide oil pressure) and that the shaft seal type will also be okay in terms of water lubrication. Running one at slightly higher revs may have some marginal benefit but not a deal breaker IMHO. Many planing hulls can’t actually operate too well on one engine as they want to go round in circles. A different matter with a semi-displacement hull with a keel or even a planing hull with a skeg keel.

Steadying sails are a rarity on modern motorboats but might be worth a try at low speeds.

For combined coastal and inland cruising my choice would be a displacement or semi-displacement hull and worth considering aft cabin boats such as Brooms, which were designed with such use in mind.
.

 

[philipdawsonladds]

You might also consider an Atlantic which is hard to differentiate from a Broom. Being Dutch they work well on the canals using a single engine as they are located closer together.

 

[ss2016]

We made that transition 3 years ago. I understand your concern over a lack of sails. I now have a single engine 400hp Sargo 31. It's seaworthy. We have made several trips to France and Scilly. I used to fly around Europe in a single engine aircraft which is not uncommon. I believe that top notch maintenance of a modern engine and close attention to the fuel should keep it going though of course there is a tiny risk. If you go for a twin I would make sure you have 2 fuel tanks. If I had two engines I think I would have them serviced out of synch with each other like I believe the airlines do.
I have no experience yet Inland. A straight line on tickover is very tiring. At that speed I helm it via the AP. Also, on its one engine it makes 6Kts plus at tickover though there is a trolling mode.

 

[kashurst]

Three things stop boat engines:
poor maintenance - easy to sort. Get everything up to date, belts, hoses, wiring etc.
overheating - make sure the cooling system is A1 and carry a few spare impellers
dirty/infected fuel - bungs up the fuel filters. - carry spare filters and the kit to change them.

Looking at boats of that vintage or any older boats to be honest, I would be looking for fuel tanks that are either relatively easy to get out or already have decent sized inspection/cleaning hatches, or fuel tanks where it is possible to create good inspection hatches. Then they can be properly cleaned out to make sure you won't have a fuel contamination problem.

 

[SC35]

Twin Engines can help with mooring in a marina, and you can limp home if one fails.
But ... maintenance costs are literally double, and there is twice as much to go wrong.

Since I started motorboating in 1999, I have had three instances where an engine "failed to proceed".

One was first time out after mis-installation of a belt. Replaced belt at sea with spare. Continued.
Another was a plastic bag that covered the intake and cooked the sea water pump impeller. It was quite choppy, so returned on remaining engine rather than trying to change.
The most recent was a electronic control unit that failed in the marina, resulting in the loss of ability to select any gear. I don't carry a spare PCU onboard

 

[simonfraser]

how many engines do the coastal fishermen have ?

 

[Piers]

With well maintained diesels the most likely cause of a breakdown will be bad fuel so good filtration and looking after the tanks with regular dosing with an additive will help in that regard. Note that the biocide type kill bug but leave debris and the enzyme type also kill bug but also help water and debris get burnt by the engines.

Having twins helps with manoeuvrability and it is a preference amongst U.K. motor boaters with the perceived benefit of redundancy. Reality is that single engines are likely to be fine if the fuel is looked after. and

Running on one engine inland is a thing (we do it) but you need to be sure that your gearbox type allows it in terms of sufficient lubrication because the shaft will keep turning (some require the engine to be running to provide oil pressure) and that the shaft seal type will also be okay in terms of water lubrication. Running one at slightly higher revs may have some marginal benefit but not a deal breaker IMHO. Many planing hulls can’t actually operate too well on one engine as they want to go round in circles. A different matter with a semi-displacement hull with a keel or even a planing hull with a skeg keel.

Steadying sails are a rarity on modern motorboats but might be worth a try at low speeds.

For combined coastal and inland cruising my choice would be a displacement or semi-displacement hull and worth considering aft cabin boats such as Brooms, which were designed with such use in mind.
.

I'd add to Greg 2's post by pointing out two considerations. First, when using one engine, you'll be crabbing to counter the asymmetric thrust from just one prob. Second., bear in ,mind that the rudder stocks will be under strain for as long as you operate on one engine.

 

[SC35]

how many engines do the coastal fishermen have ?

Errr, how safe is "fisherman" as an occupation?

Britain's most hazardous occupation: commercial fishing - PubMed

 

[oldgit]

Twin screw observations.
On water ways with locks in short order , running on one engine is pain, especially with modern planing craft with tiny little rudders and constantly en route having to compensate for lack of steerage, have to remember to stop/start an engine in the need to do any serious manoeuvres, on a busy crowded waterways such as the Thames this would be frequent.
What happens if one engine charges a battery or heats your water, fuel consumption at tickover and your fuel burn is miniscule and savings marginal.
There are also thousands of large powerful twin diesel engines out there on non tidal waters which seem to survive long periods at low rpm over many decades without obvious harm.

 

[Momac]

In my case the steering is powered off one engine only so I normally run with both on the river.
I did have an overheat not so long ago which was probably debris on the intake and the boat went okay , but slow, on one engine. And surprisingly did not try to go in circles.

If both engines fail you call for help. Putting up a sail is not an option.

I find the idea of not having a sail a bit unnerving.

I suggest keeping to river and/or making modest journeys and thoroughly checking/ servicing the engines /gearboxes until you build confidence that the boat will not let you down.

Is this sort of thing you have in mind?