Who has twins--would you do it again?

[Porkchunker]

With the price of fuel at $3 a gal on land and about $3.50 to $4 a gal over water, the question of twins verses a single might be appropriate.

I have twin F-115s pushing a 2002 2510 MV. I'm getting about 9.5-10.5 gph at cruise (4,200 rpm and 24 mph) with about 8.6% slip at the props. How does that compare to those of you with a single F-225? The numbers from those of you with MV and XL hulls would be interesting to see here.

I've discovered that a single F-115 won't get the boat up on plane, so a single motor with a 9.9 hp kicker would probably accomplish the same as twin F-115s. Thus the safety benefit of twins is probably negligble.

With the cost of fuel rising, I'm wondering if I made the right decision on my MV. If I had a DV, twins would clearly be the logical choice, but with an MV, I'm rethinking the decision.

What do you have? What are your numbers? Did you make the right decision? Would you do it differently if given a chance?

 

[susqking]

I have the same boat as you and have the f225 your numbers are very close to mine. I believe at 4200 I run 26 mph and burn around 9 to 9 1/2 gph if conditions are good. i think you f115's are doing great.

Anthony

 

[esfishdoc]

I'm happy I don't have twins on my boat. I do have the 9.9 hp Yamaha kicker for slow trolling and emergency.

If cost was not an issue.... yes I would like twins....

 

[John_Madison CT]

IMHO, a boat with Twins, that cannot plane on one engine, is not much better than a boat with a single OB, and a good kicker.

I know of few boats that can plane on one engine.

 

[Neckbone]

I have twin 90's on my 23CC right now. These are older carbed 2stroke Johnsons. They suck some gas down. If and when I repower this boat, I will be going from the twins to a single 200-225. I know my fuel consumption will drop significantly if I go to a 4 stroke or HPDI. I can almost plane on one engine, now that I have tabs, I probably will be able to. However, that isn't enough for me to have the added hassle of another engine on a boat that really doesn't need it. I'll put a kicker on it in case I ever have that emergency.

 

[Wild Rover]

I have the 2520 DV with twin 200's.....it suck a lot of gas, and will definately re-power with a single 300

 

[Parker]

I have a single 250 Zuke on my 2520 DV and I am very happy with a single because of both the fuel economy and the cost of maintaining a single as opposed to twins. Now if money object....

 

[Megabyte]

I have a single 225 OX66 on my 2520 MVSC, and am still chasing the elusive 'perfect prop', so take my fuel burn figures for what they are.

Test results here:
http://classicparker.com/phpBB2/viewtopic.php?t=522

The figures shown were for a single run and trim was not optimum, but it gives you a general idea of my fuel burn.

 

[Porkchunker]

It will be interesting to see what the new F-250 and F-300 (when it comes out) numbers will be.

Kevin, not bad...at 4,200 you are only burning about 1.5 gph more, and going about 1-2 kts less. That is ballpark against twin F-115s.

 

[TopShot25]

From what I have learned:

Twins will burn slightly more fuel then a single. (more drag, both above and below the water)

Twins will have more torque and keep the boat on a plane more efficiently and be quicker out of the hole.

As to the running on one engine thing well, I have twin 150’s on my 2520 DVSC and it will not even get close to planning. The reason I’m told was obvious once I heard it. Wrong prop. You would need a totally different prop if you were running just one engine.

I really like having twins except maybe when I’m servicing them. Those oil filters and oil cost a bunch. The safety of twins for me is more then just if one breaks down. We do a lot of hoop netting for lobsters out here. When were out at night it’s not very hard to get a rope in your prop, I’m told. A lot of the nets are not lighted and they sometimes have a lot of extra rope floating on the surface, so you can run over someone else’s net fairly easy. With the fact that your in shallow or around rocks or breakwaters if you lose power things can go bad in a big hurry. My anchor is always ready. Having twins gives me a little piece of mind on these missions also.

Oh and the boat runs like a bat out of he** also. I have my boat loaded with gear, my tower and an 80 gallon bait tank full, the boat will still jump out of the hole and top out at about 38 knots on flat water. I do wish I could get a little better fuel economy. I get as high as 2 miles to the gallon but on a normal trip I average about 1.5 nautical MPG. I will probably talk to a prop guy next year and see what I can do.

 

[Porkchunker]

Top,

Are they F-150s or HPDIs?

 

[Porkchunker]

From what I have learned:
...As to the running on one engine thing well, I have twin 150’s on my 2520 DVSC and it will not even get close to planning. The reason I’m told was obvious once I heard it. Wrong prop. You would need a totally different prop if you were running just one engine...

Hmmmmm...gets me to thinking about trying an aluminum prop with less pitch to see if one F-115 will get me up on plane. The last time I tried, at WOT, the one motor wouldn't get over about 3,200 rpm.

 

[DaleH]

I can tell you this ... a 90hp OB mounted on the stern of a mod-V fully loaded 2520 will put her onto plane @ 13 knots when using a 15" diameter 4-blade 10" pitched (houseboat) prop. I'd use a SS one and would pitch it ~4" lower than stock, 4-blades of elephant ear design if possible.

But ... hanging off the back of an OB and changing out a prop isn't fun in normal seas. I have changed out a prop while 'on the water' where we put a large green plastic bag into a net and held the net under the skeg so "if" (when :?: ?) we dropped any parts ... we would have caught them.

I would say it sure wouldn't be fun in any seas and/or in cold water ...

 

[TopShot25]

Porkchunker, F-150's

I've never tried but I agree I don't thint it would be any fun to try and change props on the water. I might think of trying to change a dinged prop if I was a long way off the beach but I don't think I would mess with the only engine I have working just to a little speed.

 

[J.A. Veil]

Dave -

What would happen if you used both engines to get up on plane and then put one of them in neutral? Could you keep it on plane with one engine, or would it drop off plane? I don't have any idea -- I have always run single engines.

 

[Porkchunker]

I'll give it a try next time I'm out.

 

[Megabyte]

What would happen if you used both engines to get up on plane and then put one of them in neutral? Could you keep it on plane with one engine, or would it drop off plane?

I'm betting that if you left the 'dead' motor down in the water, the drag would quickly pull you down off plane.

Now... if you could lift the 'dead' motor out of the water... maybe, but thats still asking a lot of a 115. :shock: