shaft sizes

[Ozzie-iv]

Hi All,

was wondering what size shafts you guys are running with your diesels..I have decided to repower my boat abecause if i waited to sell (400db 2003 8.1) I might be to old and grey to have the energy..

Anyway, since I purchased my boat relatively cheap, I figure I can afford to buy the repower option.

Looking at either cummins or cats around 425-480 hp
cummins choice sincethey are similar dimensions to my Mercruisers are these QSB5.9 380, QSB5.9 425, QSB5.8 440

Cats maybe c7 or 3216 (haven't spoken to them yet)..Anyway have someone who can do the full conversion for me

But I was wondering what shaft size, presently I have 1.5dia shafts..not sure if this is OK??

your input appreciated

Ozzie

 

[gmurtic]

Hello from Croatia!!!
I believe who ever sells you the engine will recommend shaft size and material.
Anyway on my 300 weekender With twin 300hp 6bta I have 1 1/4, and on wellcraft twin 315hp 6bta with 1 1/2 shaft.
I went to bigger shaft due to length (2,5 meters) not because I thought they were not strong enough but to reduce vibrations.

Best regards, Goran!!!

 

[fwebster]

My thought is that the B series Cummins, while likely the cheaper option, will leave you with an underpowered boat. With Caterpillar engines the added torque will require 1.75" dia shafting (roughly 82" long), and I suspect the C series Cummins will be similar.

I'm not sure you are going to like the numbers in this repower unless someone gave you the gas powered DB. Here's a partial list of what is needed:

new engines
new transmissions
new couplers
add fuel return system
manufacture or buy engine bed mounts
new shafts
new struts
new props
add diesel generator
add return fuel system for generator
replace gauges/senders
rewire the control panel if you end up with electronic engines
rewire engine primary wiring for added starting amperage
clean fuel tanks and dispose of all old gasoline
change sea water intakes, sea cocks and strainers to larger size
replace cabin carpet- you won't do this much work and not make a mess
remove and replace rear salon wall/glass doors
haul out and 60-90 days in a boat yard

If this were in the US you would be looking at $80-$90K for a repower on this particular boat. My advice would be to get a firm, not-to-exceed price for the complete conversion before beginning so you know what your total cost is going to be then decide if this is a wise decision.

 

[Asureyez]

C Series Cummings will require 2" shafts on remanufactured Diamond 450's probably the same on QSC.

Man, I'm with Frank, if you want to convert to diesel, trade this boat for a diesel model.

 

[fwebster]

6CTA's were available in 2003 and they had 1.75" shafting.............

 

[Ozzie-iv]

Thanks guys,

Yep..around $100,000 I have had a quote on the engines from Cummins which include the transmission and smartcraft,

I have someone who will do it for the price of my old gas engines...(160hrs)

a 2003 sedan bridge in my country (2003) will set you back around $560,000AUD A Riviera 2003 with low engine hours say around 300hrs sells foraround the 600+ mark.

I purchased our boat for $420,000 AUD Imported which included freight and taxes etc so I do have a little room to move.

and also, I think there will be some discounting on the engines once I compete the cats against cummins..(at least I hope they will to get my business)


OzZiE

 

[Cap10Pat]

Frank, what a list! You must've been there. Done that.
One thing to add - complete new exhaust system. A few more thousand dollars.

 

[Mick & Denise]

My 44foter with 3208 cats 375 hp had 1.75" shafts and my 50footer with 586hp has 2" shafts. I wish the 44 had 2" aslo, maybe they would not both have snapped at the cutlass bearings?

 

[Robski97]

44 footer... QSC 8.3 ...............2" shaft...

Rob

 

[Ozzie-iv]

Hi Guys,

I checked my shafts and they are 1 3/4 so at least I am in the ball park..

I have received a quote for some cats c7 ($100.000) Yanmars about 8g cheaper..can't get a quote out of cummins for the life of me so have left it for someone else.


Now!! I have decided to go down the road of trade just to see if this is an option..

I was told by (Searay dealer) I would only get wholesale value for my boat on a trade on a 44 sundancer or sedan bridge.. (The sedan bridge is the same price as a riviera (Aussie boat) of the same LOA.. The difference in trade price was $150,000 in favour of the Riviera
Both boats in Australia are around the $850,000

A 2003 Riviera low hours asking price is around the $650,000 and mine is now only worth $250,000 (Same year) if I am lucky (Remember this is Australia so please don't compare prices with USA)

I feel like writing to Sea Ray and letting them know the huge difference..the other problem is the riv guys would have contacted the sea ray dealers to work out the wholesale value.

You could see the Marketing slogan now..(mine is the only 2003 in the country)

Do your dough with a Sea Ray

In the end what does that say about investing in a Sea Ray in my country..

 

[never monday]

Let me toss out the Volvo D6 series.
Personally 450hpx2 for a 400DB sounds over powered. I'm thinking along the line of the D6.
I ran a Cruisers 460Express with these and it felt strong.

 

[tobnpr]

A 2003 Riviera low hours asking price is around the $650,000 and mine is now only worth $250,000 (Same year) if I am lucky (Remember this is Australia so please don't compare prices with USA)

Not sure I'm following you- are you comparing an 03 Riviera-diesel- with an 03 SR-gas boat (yours?)