1999 310 Silverton Express - MPG

[wakerider09]

I am considering purchasing a 1999 Silverton 310 express with alpha 1 outdrives. 5.7l Mercruiser Stern Drive (EFI). The boat has 325hrs and appears to have been well taken care of. I'd like to get a rough estimation on how many MPG I could get out of this boat at the most economical cruise speed, whatever that may be (25mph'ish?).... Lets say I have 6 adults on board with a weight of approx. 170lb per person (1,020 lbs of ppl) plus a full tank of fuel.

Is it safe to assume I could get 1.5mpg on the most economical plane speed? Also, when a boat with these characteristics is simply going for a leisurely "joy ride" (not on plane)... doing maybe 5-7mph what would the fuel consumption be? I kind of just threw it all out there, but I'm considering what type of mileage i'd be able to afford to put onto this boat... and please, I don't need anyone telling me that "if I have to worry about fuel maybe boating isn't for me"....

Thanks.

 

[JoLin]

Re: 1999 310 Silverton Express - MPG

Didn't you have this same thread going in another forum? I know I gave you answers there.

Yes, you can get approximately 1.5 mpg at around 3000-3200 rpm and low-mid 20's mph, in nice conditions. And no, it isn't safe to assume that. A bad day (wind and waves) can increase consumption significantly. In nice weather I pull 1.7 mpg/15 gph. For trip purpose, I plan for 20% for more fuel, 20% worse mpg.

5 mph will be your speed at idle with both engines in gear. You'll use approximately 1 gph per engine, maybe a bit more.

I know you don't want to hear this, but if the difference between 1.0 mpg and 1.5 mpg will decide if you can afford it, you probably can't.

My .02

 

[wakerider09]

Re: 1999 310 Silverton Express - MPG

No, the difference between 1 and 1.5mpg will not break the bank. But I do want to get a thorough opinion as people tend to go back and forth on their responses. You pull 1.7mpg on a good day, with a noticeably smaller boat (length/beam), and noticeably less HP with twin 4.3 which makes me skeptical on 1.5mpg, and the consumption between 1 and 1.5mpg is a 50% consumption difference, kind of significant. Unless one has ample money to dump on gas w/out hesitation, I think it would be irresponsible to not thoroughly investigate fuel prices/consumption before taking the plunge, and getting multiple feedback. Thanks for your post.

 

[Natesms]

Re: 1999 310 Silverton Express - MPG

I haven't ever calculated MPG however I can give you a bit of a comparison that might help.

I have a Chris Craft 33 crowne, twin 7.4's, carbed. My friend has a 31 regal, twinc 5.7's EFI. One weekend we ran the lake together, virtually identical trips. We topped off at the same gas dock at the same time at the beginning and end of the weekend.

I put $400 into my boat, he put $360 into his.

IMO - I'll happily burn the extra $40. He has to turn about 400 more RPM than I do for the same speed and works harder getting to and keeping it on plane. The lake gets rough on weekends and we pull down off plane frequently to take the wakes. I tap the throttles back up and recover my speed while he has to move them up and back down to get his speed back.

 

[MH Hawker]

Re: 1999 310 Silverton Express - MPG

I suggest golf.

 

[JoLin]

Re: 1999 310 Silverton Express - MPG

No, the difference between 1 and 1.5mpg will not break the bank. But I do want to get a thorough opinion as people tend to go back and forth on their responses. You pull 1.7mpg on a good day, with a noticeably smaller boat (length/beam), and noticeably less HP with twin 4.3 which makes me skeptical on 1.5mpg, and the consumption between 1 and 1.5mpg is a 50% consumption difference, kind of significant. Unless one has ample money to dump on gas w/out hesitation, I think it would be irresponsible to not thoroughly investigate fuel prices/consumption before taking the plunge, and getting multiple feedback. Thanks for your post.

The 1.5 figure isn't 'pie in the sky', it's about what they get. I agree that a 50% difference IS significant, and it's also a very real possibility. You can't equate what happens to a fully loaded car in bad weather, with what happens to a boat in the same circumstances. There's zero commonality between the two.

I'll just add that fuel expense represents less than 1/3 of what it costs me to own the boat. Summer dockage, winter storage, summerizing, winterizing, and the hundred and one items that need to be addressed every single year, consume the bulk of my boating budget.

I wasn't being a wise guy with my comment- fuel cost is a relatively minor matter for me compared to what everything else costs. Your situation might be different, but that's mine and tends to hold true for most that own a boat that large.

Good luck with whatever you decide.