2005 Silverton 34 ENGINE OPTIONS

[Gilligan]

I'm shopping a 2005 Silverton 34 (or 36) and would love opinions of the engines available. It's 19,000lb boat with these twin options:

5.7 gas 330HP
6.0 gas 375HP
8.1 gas 385HP
8.1 gas 425PH
Yanmar 315HP

I know nothing about diesel so I'm looking for pros and cons of the options as I shop and if one package is a deal breaker regardless of how great a particular boat may be.

Gas:
I do not like the Explosive Potential
I like the replacement cost in the event of catastrophic failure.
I am pretty comfortable working on gas.

Diesel:
I love the non-explosive potential
I fear the cost of replacement due to catastrophic failure.
Dependability - is it really that much of a difference?
Do they really last forever or is replacement inevitable at XXX Hours?

I'd love to buy end of season or beginning of next season if the ridiculous pricing ever comes down.


Looking forward to all of your opinions and experiences.

[dktool]

Yanmar if your pockets are deep enough.

[2850Bounty]

Torque is what’s needed to move that boat sufficiently.
The diesel engine is going to provide much more torque!

[Gilligan]

Price differences are insane!

[Nauti_Mike]

Diesel or 8.1 with 385HP. The higher HP one is more of a performance engine.

[kwb]

Depends how you will use the boat - low hours, low distance the 5.7 will be fine. Lots of hours, lots of miles - you want the Diesels. Not too many hours but need for speed - 8.1's are your pick. With the 8.1's (375hp) - expect about 31GPH per side at WOT. or in other terms a bit more that $360/hr. Which is about the same cost as a good therapist - which is why we buy boats anyway.

[talman]

At hull speed, they are all the same.
The cost of any engine due to catastrophic event is huge on every engine. That is why we over maintain our engines.

[Gilligan]

Great points, thank you!

KWB - what do you suspect diesels will burn at full throttle or at cruise?

as to usage?… mostly we go hull speed for local fishing, swimming and BBQ - usually well under 3 miles each way.

We do also enjoy a few weekends on the hook up to 40 miles each way and then I choose speed. Currently I get 1MPG 80 miles round trip now is $480. If we stay 3 nights I feel it’s worth it and considering that a hotel bill.

please keep’em coming - this is great!

[Gilligan]

I found a great article on calculating fuel burn. Here Is the formula and a link to the entire article.

https://www.boatingmag.com/calculati...l-consumption/

[2850Bounty]

Mike, GPH is meaningless without knowing the distance traveled.
True fuel economy will be measured in MPG!

[Nauti_Mike]

Mike, GPH is meaningless without knowing the distance traveled.
True fuel economy will be measured in MPG!

I agree with Rick. We seldom operate our engines at peak HP and the fuel/power graph is not linear so you can’t just scale down from the calculations you did.

[kwb]

Google is your friend - there are fuel curves for most engines out there. They are often generated at the engine level, hull & prop can have influence but if prop is letting engine get rated RPM it is good enough for comparison sake.

There are differing thoughts on GPH and MPG, both have use. In the case here it is about comparing engines and independent of traveled distance (GPH makes sense). If I am planning a multi-stop trip, MPG is going to help in planning my refuel points. Really MPG can get all screwed up depending on what currents and sea state are. So you have to leave a pretty healthy margin in the tank in case you encounter on of those days that you are bucking the tides and conditions don't let you run at your optimal speed.

As far as the formulas go - most modern engines are pretty effective at converting the potential energy in the fuel to crankshaft HP throughout the RPM band. There will be differences but those will be in the margins of error that you have to err to the safe side of to not find yourself out of fuel and adrift. Diesel has more potential/gallon so on that regard it will always look better than Gasoline. Pick any HP you want - it doesn't have to be peak, the GPH resulting is going to be pretty close.

[Gilligan]

Great points and great advice... as always, THANK YOU!

[PickleRick]

Wasn't the Silverton also equiped with 315 hp Cummins? Cheaper parts than yanmar. In the USA anyways

[Gilligan]

Cheaper parts are good. I’m tired of how proud Volvo is if their parts.