Single to twins

[agallant80]

Wife and I are thinking of upgrading to a 29-32 foot searay. On the 29 side (if we decide to go that route) there are some with twins and some with single motors. Has anyone gone from a single to a twin setup? I can't imagine that its twice the fuel but how much more is it? If you have twins now what is your burn rate. We have seen three boats on the 29 range.

Boat 1: Single 496 MAG
Boat 2: Twin 4.3MPI
Boat 3: Twin 5.0

All have Bravo 3 drives.

Thanks.

 

[kelleyja]

Re: Single to twins

I have - I'll state the obvious first, there are a gazillion different factors in this - vessel weight, gear ratios, prop, blah, blah, blah.

My current boat is a '30 Monterey CC with the 4.3 twins. I really like this setup. I have plenty of power to get up on plane fast, yet the I'm not burning a ton of gas in the process. IMO its a good balance of economy and power. My 4.3's burn about 6-7 GPH at cruising speed 3000-ish rpm.

My former boat was a completely different hull but of similar displacement with a 5.0. It ran 10-11 GPH at the same speed.

 

[agallant80]

Re: Single to twins

the 10-11 GPH is about what I am burning right now at around 3200. My current boat is so under powered. I have a single 5.0 MPI with a B3 and I have to keep it close to 4K some times to keep the boat on plain.

So by reading what you said is it a correct assumption that with given the same size boat you could run twins at less RPM than a single?

 

[Slip Away]

Re: Single to twins

So by reading what you said is it a correct assumption that with given the same size boat you could run twins at less RPM than a single?

Depends on the particular boat you choose, and what engine drive package it has. I assume you are looking at 280 Sundancers. With the 5.0L engines
you could probably do less RPM at decent cruiser speed. RPM would also be acceptable with the 4.3L V6's
We had a 31ft. Monterey 282CR with twin V6 220HP Merc's. and BIII drives. And it did just fine on fuel burn and had enough power for us . Our previous boat was a 26 ft. Four Winns with a single 280HP V-8, and fuel burn was very close between the two. But seriously, if you worry about fuel burn/RPM, then maybe you should reconsider getting a larger boat. Maintenance will be double, and you may also need a larger slip for the boat. It all adds up.

 

[kelleyja]

Re: Single to twins

That's hard to say. For me, I ran both at approximately the same RPM on plane - but like you said it took a little more time at WOT to get the boat up to speed with the 5.0. So probably on average I spin the twins slower but the difference was small. Gas usage wise, I spend more on gas with the twins, but not too much more.

 

[agallant80]

Re: Single to twins

But seriously, if you worry about fuel burn/RPM, then maybe you should reconsider getting a larger boat. Maintenance will be double, and you may also need a larger slip for the boat. It all adds up.

I am not too worried about fuel burn just want to know what I am getting my self in to witht he TCO of a larger boat with twins. I know there will be more fuel burn I am just wondering how much more. Logic would dictate 2 motors so 2X the fuel burn but I know that is not true.

 

[Slip Away]

Re: Single to twins

True. Make sure you can live with that claustrophobic mid cabin on a 280DA, if that is what you are considering. Lousy access.

 

[alldodge]

Re: Single to twins

As previous mentioned, it's all HP to weight ratio. The Bravo 3 is great for backing because you won't get much of the side stepping of a single prop. Twin engine setup makes it even easier. My PC27 was about the first year Formula came out offering the boat with a single engine and it had a 7.4 (330hp) in it. The 7.4 did not have enough power to move the 10K boat very well. I replaced it with a 8.2 (415hp) MPI and she runs real good now. The 29 SeaRay weights about the same as my 27, so I would suggest twin 5.0, or better yet 5.7, I'm thinking you need at least 500hp.

 

[agallant80]

Re: Single to twins

True. Make sure you can live with that claustrophobic mid cabin on a 280DA, if that is what you are considering. Lousy access.

Im sure its better than my Bayliner 255.

 

[MarkSee]

Re: Single to twins

If it were a 29 I'd go with the single UNLESS your plans call for trips to destinations where getting assistance might be an issue and the "peace-of-mind" having twins was warranted. If you really want the P-O-M and don't mind the expense then go bigger....

32s I would think finding a single would be tough. Now out here in SoCal, once you start getting into that low-mid 30s range, V-drives are greatly desired over i/os from a shear "not having to haul the boat each year for servicing" factor that a broker tells me. In that 32 foot range i/o might be the only choice.

Mark

 

[Slip Away]

Re: Single to twins

Im sure its better than my Bayliner 255.

Trust me , it's not any better. Just fancier. Once you shoehorn two people in there it is about the same.
You will see what I mean when your new wife has to use the potty at 3:00 a.m. and has to climb over
you to get in and out of the mid cabin.

 

[alldodge]

Re: Single to twins

Only thing I would say about V-drives is your fuel efficiency goes way down. I call them tunnel drives (not the real name) because a portion of the hull is made to house the top of the prop. When up on plane some of the top of the prop is above the water and therefore pushes the water it moves against air. Folks at my lake like the lower maintenance cost as Mark See stated, but they hate the fuel usage increase. I see most of them just puddeling around about houseboat speed.

 

[QC]

Re: Single to twins

There are many twin I/O Express cruisers out to 35+ ft. My recommendation is review fuel use and power options at BoatTest.com. Many of the boats you are considering have the speed vs fuel data there if that's what you want. There is no magic formula to consider a single vs twins. It's all about the specific boats, applications, desired speeds etc. With express cruisers I would have a hard time justifying singles above 28 ft. The 280 Sundancer, however, does test at 41.7 MPH though with a single 350 MAG. In practical use I am guessing it would really be a 35 - 37 MPH boat. If that's OK, then go for it. I do not worry about getting these boats on plane anymore with dual prop drives. They make single small blocks perform like single prop big blocks out of the hole.

 

[tpenfield]

Re: Single to twins

Wife and I are thinking of upgrading to a 29-32 foot searay. On the 29 side (if we decide to go that route) there are some with twins and some with single motors. Has anyone gone from a single to a twin setup? I can't imagine that its twice the fuel but how much more is it? If you have twins now what is your burn rate. We have seen three boats on the 29 range.

Boat 1: Single 496 MAG
Boat 2: Twin 4.3MPI
Boat 3: Twin 5.0

All have Bravo 3 drives.

Thanks.

Hey Drew;

I upgraded from a single 24 foot Cuddy to a 33 foot Sun Sport with twins. Definitely go with twins once you get up into the 28+ foot range. Large boats with single engines fall off plane way too easily . . . you will go crazy with all the revving to get back up on plane, etc.

Fuel burn is less per engine, but it is less X 2, so it ends up being about 50% more total consumption. If you are concerned about fuel consumption, go with the sun sport models in the 28 - 30 foot range (Sea Ray has something in that size range IIRC). If you go with a full cruiser, then expect to burn a bit more fuel.

I put somewhere between 40 - 50 hours this season on my Formula 330 and burned 370 gallons of gas . . . so less than 10 gallons per hour overall average with twin 454's.

As far as cruising, my boat runs like it is on rails with the twin engines. I set it a 2400 - 2600 rpm to cruise and rarely have to touch it. You will enjoy the extra space of a larger boat with the type of cruising that you do, as per your blog.

I would recommend SeaRay, Cobalt, Chaparral (285 SSI), or Formula in the 28-30 foot size range as a nice upgrade. Or you can be like me and go for something a bit over 30 feet.

 

[Slip Away]

Re: Single to twins

Great suggestions.Ifthe OP is looking for cuddy cabin boat, but I think he is considering another express cruiser. The boats mentioned, 285SSi, 280 SS Sea Ray (No longer made) and even the Formula 280SS only have 5.0' of headroom. Fine if you are vertically challenged, but not compared to the 6'2"+ he would find in an express cruiser like the 280DA. Plus, the cuddy cabin boats don't have a mid berth, only the convertible v-berth.

 

[agallant80]

Re: Single to twins

You will see what I mean when your new wife has to use the potty at 3:00 a.m. and has to climb over
you to get in and out of the mid cabin.

HA!! That has happened every time we have slepped on the boat this year.

 

[agallant80]

Re: Single to twins

Well perhaps you guys can help me find the next boat.

Full Beam
Express cruiser
Can get on a trailer (NC you don't need permits for wide boats)
$90K

I like the idea of twins because I have ran in to several people this summer at the docks with a 28/29 foot boat with a single outdrive and they hate it when they have to dock.

I am going to do some poking around at the Annapolis boat show in a few weeks.

 

[Slip Away]

Re: Single to twins

Okay, I'll start the suggestion process.
Used 2006 Chaparral 280 Signature, Denver, Nc - 28078 - BoatTrader.com

Permanent V-berth a plus. Mid cabin if needed. Pretty loaded boat, low hours , twins, decent price.

 

[HT32BSX115]

Re: Single to twins

Well perhaps you guys can help me find the next boat.

Full Beam
Express cruiser
Can get on a trailer (NC you don't need permits for wide boats)
$90K

I like the idea of twins because I have ran in to several people this summer at the docks with a 28/29 foot boat with a single outdrive and they hate it when they have to dock.

I am going to do some poking around at the Annapolis boat show in a few weeks.

For the above requirements,
My choice is a 2000+ Formula 370 SS With either Twin 496/Bravo III's or 6.2L +B3

The 350 SS has a rear "cabin" but there aren't any "older" ones out there so they're still pretty expensive!.

Okay, I'll start the suggestion process.
Used 2006 Chaparral 280 Signature, Denver, Nc - 28078 - BoatTrader.com

Permanent V-berth a plus. Mid cabin if needed. Pretty loaded boat, low hours , twins, decent price.

There is a Volvo powered Chap up here in the NW for sale with Volvo Penta power but with the "Composite"(coated) XDP drives. RUN AS FAST AS YOU CAN FROM ANY VOLVO "COMPOSITE" DRIVE

 

[Slip Away]

Re: Single to twins

It appears the 280Sig I linked has DPS drives, not XDP. Also a Formula 370SS slightly exceeds the OP's length requirements, and I suspect his budget as well. It does have headroom though :joyous:

Well, looks like this thread has been hi-jacked and will await new post this winter titled "Which of these cruiser's should I buy ?"