330 gas to diesel conversion

[Tony Clark]

Hi all

Firstly, I am a new member here and secondly I live in the UK where petrol (Gas) is currently costing just short of $8 per gallon :smt013

My boat is a 1998 330 sundancer, I purchased the boat from the US last year with one engine stripped down to the blocks, and the other in a siezed condition, this suited my needs as it was to be converted to Diesels over the winter period.

Thye work is now complete and sea trials are underway to determine performance and economy figures, however as I have not been able to operate the boat in it's previous glory (twin 7.4 MPI 310 hp gas engines, turning 17x17 NiBral 3 bladed props through velvet drives with a ratio of 1.5:1) and therefore I have no actual performance figures to compare against.:huh:

I have removed the gas engines and mated the Velvet drives to twin Steyrmotor 246 k42 these give 250 hp (dyno certified) and and rev to 4200 rpms at WOT, and at present we have just finished running in the engines as per the manufacturers recomondations, whislt the boat was out of the water the props were overhauled and following discussions with prop specialists and using the Prop calculator program on www.boatdiesel.com I had them resized to 16x16.

The boat is sitting with full tanks (800 lts) fuel and with five people onboard we achieved an average speed (gps) of 21 kts running up and down tide in a slight sea as for fuel burn it is to early to tell as we havent yet taken the boat out for a decent run and until we do this and top up the tanks again fuel burn is at best, a guess.

I would like to hear from 330 owners with V drives and 7.4 V8's that have some actual performance figures as the factory info could be wildy optomistic.

I will be very happy to post pictures or info for those interested.

Regards

TC

 

[fc3]

I believe this is the information you seek. Just Ducky has Merc 7.4 MPI engines, V drives, and 17x17 3BC NIBRAL propellers. Fuel burn vs. GPS speed is charted below. The fuel burn was read from each engine's EFI processor via a Rinda EFI diagnostic tester. Speed data is from the GPS system. Speed are two way average to account for wind and tide.

My results correspond pretty closely to those published on BoatTest.com for their test 330DA. You need to be a member of their site to see old, archived tests, but membership is, or was, free.

Best regards,
Frank

P.S.

Hey! This ancient chart's fuel costs are back in style. Happy days are here again!

... Well almost. If it weren't for the crappy economy and osama...

and nancy

and harry

and barney (not the big purple one)

Well you're from the U.K. so they're not your problem.

 

[Tony Clark]

Frank

Many thanks for the table, can you tell me the Fuel load,Pax load and what your empty boat weighs as you are aware these can have a big effect on performance.

Mine "Sanctuary" was weighed in at 16000Lbs (7250 kgs from the crane scales) with full tanks and "light" cruising kit. Sanctuary has a 4.5 kva Westerbeke, radar, 10 metres of chain and 50 metres of rode so I would have thought that this was a "typical" weight for this boat would you agree ?

Cheers

TC

 

[tdappleman]

TC - sounds like a very cool project! Can you give us more details on the work and of course post some pictures? If you don't mind me asking - what was the cost of the swap?

 

[Tony Clark]

Travis

I purchased two factory rebuilt units from UK dealer for £15K inclusive of all taxes for this I got two zero timed warrented engines with diagnostic software and bellhousing to suit the Velvet drive boxes, along with tacho's temp, gauges, starter switches and wiring looms.

I did all the installation work myself and apart from some slight reworking of the stringer height (for the new rear engine mounts as these were taller than the Mercruiser units) it was a fairly straight forward fit.

These Steyrmotor engines are 60 hp less per engine than the Mercruiser units removerd but each engine is 110 kgs lighter and thats one reason why I seek performance details as I think that at present I am underproped.

I think that you will agree it is a tidy installation and whilst the engines and boxes were out I re did the bilge paint and used the existing longitudinal exhaust baffles.

I also feel that based on the few hours we have done to-date sea trialing the boat that the trim tabs could be bigger as she runs very bow high ( however this is my first ever boat and I have little experiance to draw from)

I will post you some pictures of the installation as soon as i figure out how to resize them (reading forum info on that subject just now)

regards
TC

 

[Tony Clark]

Does anyone know how many 330's were built ? and what the main problems, or critisms (if any) this marque suffered.

TC

 

[tdappleman]

TC - Thanks for the update and the pictures. Looks like a very nice install - great job on being able to do all of that yourself!

 

[BadaBingII]

TC,

I had an older 330 Sundancer with twin 260hp gas. Cruise was 20 knots at about 23gph total.Top speed was 29 knots.

Always thought mine could use bigger tabs too. My top speed was best with tabs about 1/2 way down.

That is a very nice installation!

Let us know how she runs when you get her all dialed in.

 

[Aarrhh & Aarrhh]

How difficult was it to re-work the fuel system?

 

[tobnpr]

Nice looking install. Quite impressive given it's your first boat.
You mentioned you think you're underpropped; and said they turned up to 4200 rpm- what is the recommended WOT rpm's?

 

[fc3]

Very nice. Just Ducky has every Sea Ray option except the crossover fuel system. So she has air conditioning and a generator. I don't know her weight, but when I did the test runs above, she was at full fuel, full water, and empty holding tanks. Also had two people on board and a moderate load of cruising gear.

How do you manage fuel for the generator, since it appears to be the gasoline version? If you have gasoline aboard then you may have an explosion hazard since most diesels do not have ignition protected electric systems. I don't know what the regulations are in the UK that pertain to that, but you need to be cognizant that a potential hazard may exist.

Best regards,
Frank C

 

[Larry]

TC,

Very nice set up! I agree with Frank's point though about the geny, I think your this far in you are going to have to upgrade the geny. I have found on my 33 that I need almost full trim tabs to give me the most efficient ride with anything less than full tanks of fuel. I have been considering changing my anchor rode to all chain, this will add about 300 lbs. to the very front and with some tests we have done with sand bags I believe this is a functional solution to carrying allot of trim tab, and reducing drag.

Performance info:

3000 / 20 kts / 24gph
3200 / 23 kts / 27gph
3400 / 25 kts / 29gph

4500 / 34 kts / WOT

I have 17 X 17 3/4 3 blade with mild cup

 

[Tony Clark]

The fuel tanks on mine were for Gas/Diesel use and therefore already fitted with two 3/4 threaded (one blanked off) fittings and as you are aware the gas system only needs one supply line for each engine whereas Diesels require two (supply and return) per engine.

I utilised the original selector/Isolator valves and fabricated two alloy stantions to mount the new Racor 500 filters/selector valve on, one stantion mounted on the port side near the port tank and the other mounted on the Stb side, then it was just a simple plumbing job from tank to selector to filter to engine and return pipe from the engine back to tank . I also run 2x10 mm copper tube from the port valve to the stb valve to facilitate crossfeeding of fuel. I used copper as these pipes run over the engine turbos and clipped every 10 inches as this would give better protection in the event of a hot gas leak in that area.

As for the WOT "there lies the Rub" as we say, because the engines are electronically controlled I can't over rev them and therefore I am reliant on either trial and error regarding prop selection.

I had the props resized as I dinged one during the running in process (DOH!!) and whilst I was not able to run at full Rpms during this process for any length of time due to sea state and throttle restrictions on the running in time never falling into line I had to take a punt on what size to go for and the prop shop advised 16x16 (old props 17x17) so this is what we did and had them both balanced.

However during one run whilst running in we achieved 25 kts at 3800 rpms in a moderate seas only to be told to slow by the "Admiral" as you seem to call when the boat did actually get very slightly airborn. That was exciting I can tell you.

TC

TC

 

[Tony Clark]

Frank

Bugger !!!! I am not aware of the status of the Steyr engines regarding "Ignition protection" and your point is a very good one for consideration, I will check with Steyr today.

I say Bugger!!! because I did think about leaving the genset out and fitted the engines first for the sea trials and I have only just put the genset in when we lifted the boat to remove the props for repair, I can tell you that it was a very tight squeze and at one point I thought that I had cocked up on the measurments. That said if the genset needs to come out again it will.

I had planned to have a seperate tank fabricated for the Gas (we say petrol) and thought about 30 lts would be suitable ?.

Thanks for the responses I have something now to go on and other issuse to resolve.

TC

 

[dpmulvey]

Frank

Bugger !!!! I am not aware of the status of the Steyr engines regarding "Ignition protection" and your point is a very good one for consideration, I will check with Steyr today.

I say Bugger!!! because I did think about leaving the genset out and fitted the engines first for the sea trials and I have only just put the genset in when we lifted the boat to remove the props for repair, I can tell you that it was a very tight squeze and at one point I thought that I had cocked up on the measurments. That said if the genset needs to come out again it will.

I had planned to have a seperate tank fabricated for the Gas (we say petrol) and thought about 30 lts would be suitable ?.

Thanks for the responses I have something now to go on and other issuse to resolve.

TC

30 litres ~= 7.5 gallons. My generator is the same as yours and burns approximately 1 gallon per hour.

I don't know about your side of the pond, however, westerbeke here has a rebuilt program where you can buy an rebuilt gennie for about 1/2 the price as new with damn near a new gennie warrantee.

Nice install. That engine is giving Yanmar a run for the money over here. They sip fuel.

Even though the engines are electronic, your WOT or electronic override should be posted in the literature. Even though the engines are of less HP, I would have thought you would have had to go up in pitch and decrease diameter to compensate for the massive torque a diesel puts out compared to a petrol engine. Diesel 330's were not uncommon outside the US. I wonder if Sea Ray's middle east or european division has the specs that could at least get you in the ballpark for correct props. I'm thinking a 15.5 by 19 for starts. That is just a SWAG.

 

[Tony Clark]

David

I did look into getting a diesel genset but the new price £5K was prohibitive to say the least, I need to find out some more info such as does the petrol (Gas) genset and the Diesel engines mate up to the same alternator, if so then it would be far cheaper for me to source a rebuild diesel engine and use my Alternator.

I will get in touch with Westerbeke and find out as it would be a option to consider if my Steyr motors are not ignition protected.

The only problem with the above option is that I remember a westerbeke rep telling me at a boat show that their diesel sets are way noisier than the petrol units even with the sound box option, any comments from diesel genset owners very appreciated.

I am finding out the hard way that Prop matching makes "VODOO" look like a science !!!!

Larry

I like your thinking on the "chain" idea I will load up the chain locker next trip and see what effect it has.

Thanks for the figures all this info is helping refine my thoughts and understanding.

TC

 

[fc3]

Tony,

Do you have a fuel burn chart for you diesels? Most diesel engine builders provide such data. If so, you should know from the chart that at X RPM the engines should burn Y fuel (could be rated in gallons, pounds, litres or kilograms per hour) Then you need to measure the fuel flow on your boat at those same RPM levels. Now armed with that information you can easily tell how far off the mark your propellers are. If the chart shows that at 3000 RPM the engine should burn 10 litres per hour (I like round numbers) but your readings show that you are burning 12, then your props have too much pitch and the engines are overloaded. But it sounds more likely that the reverse situation is true. Where the chart show 3000 RPM / 10 lph you actually are burning 7, then the propellers are way off and need substantial adjustment. But if you are burning 9.9, then you might be close enough and just need a tiny bit of tuning.

Your engine distributor and propeller shop can help you here.

Best regards,
Frank C

P.S. I like a good engineerin problem in the evening.

 

[dpmulvey]

David

I did look into getting a diesel genset but the new price £5K was prohibitive to say the least, I need to find out some more info such as does the petrol (Gas) genset and the Diesel engines mate up to the same alternator, if so then it would be far cheaper for me to source a rebuild diesel engine and use my Alternator.

I will get in touch with Westerbeke and find out as it would be a option to consider if my Steyr motors are not ignition protected.

The only problem with the above option is that I remember a westerbeke rep telling me at a boat show that their diesel sets are way noisier than the petrol units even with the sound box option, any comments from diesel genset owners very appreciated.

I am finding out the hard way that Prop matching makes "VODOO" look like a science !!!!

Larry

I like your thinking on the "chain" idea I will load up the chain locker next trip and see what effect it has.

Thanks for the figures all this info is helping refine my thoughts and understanding.

TC

There is the option of placing a portable petrol tank on the transom platform. That eliminates one problem. Perhaps a gennie enclosure would eliminate or at least mitigate the the problem. I don't recall how petrol is priced overseas, however, in the US, petrol at a shore station is usually 30 to 40% cheaper than at the marina.

WRT the "chain idea", WADR, it won't work. Saint Max carries `300 feet of chain and she still needs tabs to remain on plane regardless of speed and load.

I spoke to Bennett about the problem. They told me that Sea Ray was informed that the tab configuration on the 330 was grossly inadequate for the task at hand. Bennett recommended attaching an extension to the existing tab. Saint Max has 22x9 tabs. Bennett recommended I extend them to 22X15. I may go to 22X18 which would in effect double the tab size. I questioned Bennett as to the durability of the extra stress on the hydraulics. Bennett told me the hydraulics were well able to handle the extra load. In addition, the stress would not be as great because the angle of the tab would not be as great as if there were no extension.

A fellow who had a similar problem on a mid size Regal and did the same thing. He maintained speed at a lower RPM and improved his tracking as well.

I need to look at the newer Sea Ray's. I believe I need to eliminate the 90* downward turns in the tabs to increase effeciency.

HTH

 

[LMBoat]

I don't neen much tab on mine while on plane other then side to side trim <I'm strb heavy>. I have 150 ft of chain in the anchor locker. When I bought the boat, I was not happy with bow high attitude at take off either. I did talk to SR and Bennett. Bennett gave me new hydro cylinders with a longer travel <2 1/2" I believe>. This solved the problem had has worked great for the last 7 years.

 

[Tony Clark]

Frank C

I have the facility to plug in my laptop to the engine ECU and monitor realtime data such as rpm, fuel flow (albeit injector open time and this is converted to fuel flow), water temp, oil temp, oil pressure, and most importantly Manifold pressure this should give Steyr the info needed to determine output so I will go for a run as soon as the seas are calm and capture some data for the to analyse.

David

I too suspect that the boat is undertrimmed and this could form some part of my fix, however i would think that removing the 90 deg downturn at the outer edges would be detrimental to the efficiency of the tab as the pressure is greater under the tab than above (when set down further that the horizontal hull line) and without the 90 deg downturn water would "spill" along the sides and reduce the tab effectiveness.

Larry

I too will contact Bennett and see what if anything the recommend.

Thanks to all for your time and input.

I hope that I can be of help to you guys when you need it

Regards

TC