Best Diesel for a Tophat

[karl010203]

Our tophat has an outboard, and do dream of an inboard... quieter, no smoke, no lifting and turn the key all appeals. Especially after one of our last trips where left windless motored for nearly 6 hours... left pretty deaf at the end of that *what*

So I do dream of retrofitting a diesel and have previously posted regarding that... but would really like to know what inboards others have had sucess and failure with, same for ideas on locating fuel tank, best prop type, sound proofing, etc.

Any thoughts greatly appreciated

Karl

[storm petrel]

Hi Karl,

I have given some information about my inboard on other posts, but for the record. I have got an old Yanmar 2QM15 twin, raw water cooled and thrity years old(probably been with the boat since new). It always starts easily and just needs the oil, oil filter, fuel filter and impeller changed annualy (costs about $200-$250 to have it done by a mobile mechanic and would be easy to do yourself). I have never needed to crank it, but I think I could give it a go if I had to.

The shaft is off set a little but it drives the boat at the hull speed easily and it also goes backwards (with a little prop walk). An offset prop also means I could get the prop shaft out, if I had to, without having to remove the rudder. The prop is a fixed two blade and the shaft has a dripless stern gland, that to date has lived up to its name (my mechanic looks at it each year and just says don't touch it unless it starts leaking). I have to run the motor for about 25-40 minutes to get out of Brisbane Waters and again for this amont of time time when I come back in. I don't have a solar panel, but this amount of running seems to keep the battery well charged.

The Engine is under the stairs and cockpit and is sound insulated with standard Bias Boating Engine stick-on Engine Sound Insulation. It just chugs along without being too intrusive, though it is a bit noisy down below if you are there for a long period. Fuel consumption is about 1 litre per hour at 5 knots. I have a 60 litre stainless steel diesel tank under the starboard bunk with a simple machanical fuel guage. I only top it up a few times a year under normal usage (out about once a week).

I think any reconditioned yanmar 8 or 10HP would be fine, my 15HP is probably overkill.

You may miss the space under the cockpit but you will enjoy the convenience of the inboard. Let us know how you get on.

Mark

[mmts]

Hi Karl,

I have a Mk1 with a Volvo MD1B (10HP)which is probably original to the boat. The only drawbacks I see with this engine are all the servicing points are hard to get to.......raw water pump especially, some of the more modern engines have these at the front of the engine. The engine is quite large and has a combined starter generator setup.......which is very expensive to repair and find parts for.....and a huge flywheel up front. This engine has a hand start capability......but only for a gorilla, tried once, no make that a thousand times, just can't seem to get up enough momentum/leverage in such a small area. then again throw in a lee shore or a panic situation I might just be able to get it going. Having said all that this engine runs real sweet and is very frugal on fuel. My prop shaft exits directly aft in front of the rudder, I think the offset like storm petrels would be a better arrangement..... a lot of rudder and keel in the way to reduce efficiency on my boat.

Regards

Mark
Anne Marie

[Dolphin]

Hi Karl and all.
I have just (April 2009) replaced a BMW Marine Diesel (Hatz D12 12HP single cylinder) with a Volvo D1-13 12HP twin cylinder freshwater cooled. The cost was, sit down, k$10. The installation cost k$4. We, sorry, Tony Clapson in Burraneer Bay Pt Hacking, did some additional work on the stern tube and cutlass bearing. That was an additional $1024 and involved removing the cutlass bearing at the shaft entry to the hull and renewing the skeg bearing. The brass stern tube was leaking and it was replaced with a fibre glass tube. Having only one skeg bearing allows the motor to float.
It is a very much happier Top Hat and runs like a boat should. Its also quieter and smoother. It currently has 3.3 hours on the timer and has to be run in for 10 hours. Next service is 50Hrs. It doesn't have a crank and can only be electrically started. It has a 150Amp alternator on it.
The Hatz was a light weight diesel and raw water cooled. The Mixing Elbow (exhaust manifold) was priced at $874.95. The Volvo's was $350. All of these types of elbows need to be replaced every 5 years. It was a major cost. It was the cause of the Hatz running hot and it was just rusted up.

The Hatz alternator had given up the ghost several years before and we had been running off the solar panel. The cause of that was the O rings in the head leaked and let sea water run over the alternator. Its similar to a motor bike in that it actually sits under the flywheel with permanent magnets in the flywheel and is actually made by Ducati. It was rated at 25A.

Some of the other options I persued were for other brands of diesel, Yanmar and Nanni. The price of the other brands spares were more expensive than the Volvo and the purchase price of say a Nanni was about k$2 less than the Volvo. Filters etc were also cheaper for the Volvo. Installation costs were the same for all brands but Tony was a Volvo agent and part of a large dealer network. The final straw was when I was putting the Hatz back together and I broke the head stud. All the studs had corroded and had pits in them. If you get offered a Hatz don't take it.
I couldn't have sold the boat with the broken diesel in it .
Its a big mod to undertake and It would probably be better to buy a new boat with a good diesel in it.

All the best, Greg.
Felicite.

[karl010203]

Hi Greg

Holy crap that is not cheap... appealing but not cheap.

In light of this, the outboard is not a bad option, certainly easy to maintain etc

Plan b is to make a sound proofed box around the outboard... and a lid over the top - I guess with some consideration of breathing ability etc... has anyone done this sucessfully?

[Tales]

I have seen one Top Hat with a cover over the outboard.
My concern would be condensation and corrosion but it might be worth a try.
When we changed over to a modern 4 stroke the noise was less than half.
Further noise reduction was achieved by plugging the little exhaust bleed in the leg.
I tapped a 4mm thread and screwed in a 4mm screw.
The screw is removed when stopping and starting and I really only fit it if we are motoring for a long spell.
The motor idles ok with the plug in and starts well too but I feel the hole must have a purpose.
Some motors have multiple holes so this may not be practical.
Have given thought to drilling out and fitting a hose adapter (with a hole the same as the original one) and running a bit of flexible tube over the transom to get rid of the gas.
I originally plugged the hole to rid the cockpit of carbon monoxide which it did admirably.
Cheers,
Tom