New build power, do I really need twin 300's

[GeorgeV73]

Been lurking here for quite a while. Great forum with a lot of great info.

I'm in the middle of Having a 30' aluminum hull built. Specmar hull# 1457.
The rigged weight, full of fuel and twin 300's is 7,800lbs .

My question is, do I need twin 300's? My main objective is economy not speed. I see test bulletins from Wooldridge, Hews and Pacific and see quite a few equipped with twin 200's that have similar hull weight. I would like to go with twin Suzuki DF200AP. I will be cruising at 25 to 30mph 90% of the time (or what ever speed has the best mpg). This boat will be used more for cruising and camping than fishing.

I understand all the benefits of going with the most power possible, but do I really need it. I could care less about top speed.

Hopefully someone on here with a similar style boat can give me some guidance.

Thanks

 

[bman440440]

Been lurking here for quite a while. Great forum with a lot of great info.

I'm in the middle of Having a 30' aluminum hull built. Specmar hull# 1457.
The rigged weight, full of fuel and twin 300's is 7,800lbs .

My question is, do I need twin 300's? My main objective is economy not speed. I see test bulletins from Wooldridge, Hews and Pacific and see quite a few equipped with twin 200's that have similar hull weight. I would like to go with twin Suzuki DF200AP. I will be cruising at 25 to 30mph 90% of the time (or what ever speed has the best mpg). This boat will be used more for cruising and camping than fishing.

I understand all the benefits of going with the most power possible, but do I really need it. I could care less about top speed.

Hopefully someone on here with a similar style boat can give me some guidance.

Thanks

Here is how I think when it comes to power for a boat... go BIG!! the reason for this and it has done me well over the years (2 smoke outboards going over 4000 hours) is because the larger engine(s) will be doing less work for the same conditions you are running in... IE in your case the twin 200's running at 25-30 MPH at (these percentages are not accurate and just for an example) 70% load and the twin 300's same speeds and running at 50% load... therefore better mileage and longer life. A good example was my Hydrasport that I had came with a 175 on it... when it croaked I put a 225 on it (Max rating for the hull) and my mileage went up by 30%... that's my opinion and you can take it for what you paid for it.

 

[GeorgeV73]

Thanks for your input, I really appreciate it.
I understand that less HP will have to work harder but then again fewer cylinders (less displacement) will burn less fuel when compared to a higher displacement engine at the same rpm. I've looked at a lot of test bulletins for similar size/weight boats and the main difference I see between twin 200 and twin 300 is top speed and a higher cruising speed for the higher HP engines. Otherwise the fuel consumption is the same and in most cases a littler better for the smaller HP engine.
I am leaning towards the 300's, everyone says get the most HP but I havent heard from anyone with a similar boat with twin 200's and how they perform for them.

 

[bajabills]

Is this 600 hp going on a 30' aluminum?
What bman said is correct.

While you may not run top speed, on a flat day you might. And at 80% the engines gonna pay you back
In dependability, less repair etc.....= better trips, less headache.

Btw, my buddy's got a 32x12 aluminum with 700 diesel hp. The boat moves when you want it to.

 

[GeorgeV73]

Thanks for the feed back.
Yes it's a 30'X10.9' aluminum and rated for 600hp. The hull is a deeper V, 20deg dead rise but has a large delta pad as well as reverse chines and lifting strakes. Should be be pretty efficient and not require as much power as a comparable size fiberglass set up. I'm sure there would be certain days I'd wish I had more power if I went with the 200's, but here in the Puget Sound it seems like there is always a little chop. Not running pinned very often, plus there are logs floating around everywhere. I do hear your point on having more HP and it makes sense.

Thanks again

 

[TAPOUT]

You have to think about the weight you will be carrying and your average sea state. larger displacement motors will keep your boat on plane with loads and work less. Nothing worse than an underpowered boat. Also, think exit strategy, you rarely hear someone complain about a boat that is powered to capacity. Additionally, consider if there is a failure of one motor. Will the other one get you on plane? step up and get the 300's.

 

[Ali]

No brainer IMO. You aren't going to burn more fuel with the 300's over 250's.

Give yourself some cushion for fat guys, ice and boat full of fish.

The Steiger 31' I'm building has twin 300 yami's on it. It has plenty of power now, but after I get done with a bait tank, tower and 2 tons of gear I think it will be perfect.

 

[samohr]

Most boats with that beam have v6,s on them, unless you can verify weight, ie one that has already been built, the i4 will be risky. That weight seems suspect for boat with that beam. Prop options are much better on the v6’s as well.

North river 2900 os has less beam, 7k lbs, no motors, dry, bare boat.

Get the 300’s.

If your truly looking for economy, look at diesel, much cheaper fuel, single diesel will burn 10-11 gph at cruise, twin 300 will be 20 gph.

 

[Walker Inc.]

I have a 30’x10’10” aluminum. I weigh in at 12000 fuel and 250’s with minimal gear. I think your weight is off. Regardless, my re-power will be 300’s or 350’s. Don’t underpower your boat. There is no replacement for displacement in moving mass around. I will take a lower revving V6/8 over a wound up 4 cylinder. Tech bulletins are for buyers. Not real world use and conditions.

 

[GeorgeV73]

I have a 30’x10’10” aluminum. I weigh in at 12000 fuel and 250’s with minimal gear. I think your weight is off. Regardless, my re-power will be 300’s or 350’s. Don’t underpower your boat. There is no replacement for displacement in moving mass around. I will take a lower revving V6/8 over a wound up 4 cylinder. Tech bulletins are for buyers. Not real world use and conditions.

View attachment 921159

Thanks Walker Inc. That's exactly what I needed to hear from someone with a similar boat. You may be correct on the weight, designer (Specmar) says 7,700# but my builder said exactly what you said, the rigged weight looks low.

I'm on the hunt for power right now, seems all the best deals are in Florida. I'm tireless scouring every corner of the net for the deal of the century. Suzuki, ETEC G2 and Honda have been the top three. Might rule out Honda now since they don't have a 300.

All the feedback has been much appreciated.

 

[Walker Inc.]

Rule them all out. Etecs suck and burn oil. They are not cheaper to run. Honda can’t design a cowl that doesn’t leak, and uses basically a car window actuator that fills with water and fails from the leaky cowl on the IST 250’s.
Suzuki is great but not a lot of dealer support around where I am. You have master marine and Performance up where you are.

I am a Yamaha guy and it’s my preference. Even when they have failed Yamaha is like Nordstrom. It’s fixed.

The hull truth moves a lot of motors if you are looking for used low hour

I have a set of 3.3L 250’s with 5,000 hours still running strong with all rigging. Gets you running now. Yamaha does build a mechanical 300 now. You could order a set and just have to swap engines. Let me know

 

[GeorgeV73]

I have a few quotes right now,one is 37k for twin 300 Zukes with all controls/wiring and gauges , excluding tax and installation. This is a guy my boat builder uses

Another quote for 2 low hr ETEC 300 G2, installed 33k

And another quote (Florida) twin 2017 Suzuki DF250APX with controls gauges and all wiring shipped to Wa, 34k.

I have searched every inch of Craigslist in Florida, Ebay, The Hull truth and have found some okay deals. Twin, low hour Yamaha F300 for 50K, that's used engines and no controls of any kind. Yamaha is out of my price point. I've owned many Yamaha's, of all sizes over the years and agree, they are great engines.

I open to lightly used but 5000hrs is a bit much for me. Who knows, in another week I might be reviving this thread and asking you what you want for them.

 

[Walker Inc.]

I would go Suzuki’s. It’s definetly on my radar when I do it next year. They are substantially cheaper, and have a great warranty. Fly by wire is pretty easy to rigg.

 

[af dreamer]

too much is never enough,work less and work longer IMO.Tom

 

[clevel]

Been lurking here for quite a while. Great forum with a lot of great info.

I'm in the middle of Having a 30' aluminum hull built. Specmar hull# 1457.
The rigged weight, full of fuel and twin 300's is 7,800lbs .

My question is, do I need twin 300's? My main objective is economy not speed. I see test bulletins from Wooldridge, Hews and Pacific and see quite a few equipped with twin 200's that have similar hull weight. I would like to go with twin Suzuki DF200AP. I will be cruising at 25 to 30mph 90% of the time (or what ever speed has the best mpg). This boat will be used more for cruising and camping than fishing.

I understand all the benefits of going with the most power possible, but do I really need it. I could care less about top speed.

Hopefully someone on here with a similar style boat can give me some guidance.

Thanks

Sounds like a lot of horsepower for the weight, but then I don't know anything about your hull design. If it is a modified V hull I would say 2x 200 hp should be fine.

 

[GeorgeV73]

It's 20deg at the transom but has a fairly wide delta pad, you can kind of see it in the pic but the welders are in the way. Also has reverse chines, not in place in the first pick but you can see the profile. There will also be 2 lifting strakes on each side of the hull. Not sure how sharp the entry is at the bow but it should be a fairly efficient hull.
I would love it if twin 200hp would do the job, that would save me a a lot of $. Most say go with the max power though.

 

[miaf]

Some good info here. I would also post this question on The Hull Truth website. That’s site seems to have a lot more technical posters.

 

[MYNomad]

I understand that less HP will have to work harder but then again fewer cylinders (less displacement) will burn less fuel when compared to a higher displacement engine at the same rpm.

I believe there is a flaw in your logic. To move your boat at a particular speed will require a particular horsepower (assuming props are the same size and that weight isn't changed). And producing horsepower requires the energy that is stored in gasoline (effectively constant on a per gallon basis), multiplied by efficiency. And modern engines are all close to the same efficiency across a wide range of outputs. A good rule of thumb is that 1 gallon (of gas) per hour can produce a constant 10 horsepower for that hour. So, whether you have a pair of 200 (max) hp engines or a pair of 300 (max) hp engines, if they are equally geared and propped, and if they are moving your boat at a particular speed, then the 200's have about the same efficiency and are consuming about (could be more, could be less) the same amount of fuel to produce the requisite horse power. Now the 300's are a little heavier, so you will be pushing a little more weight, which would require a little more HP (at planning speed, likely in proportionate to total weights), but probably immaterial.

 

[ShadBurke]

Get a pair of yamaha f500s......

If the wallet has the thickness.......

 

[GeorgeV73]

I see how what I said can be interpreted as flawed. I'm basing some of what I said on performance bulletins from similar sized boats with very close hull weights. Case in point the Wooldride 29. They tested the same boat (similar to what I'm building) with Twin 250's and with twin 200's. Obviously the 200's were slower at WOT but had far better numbers at 3000 rpm than the 250's had.

 

[sbsurfer]

I have never ever heard of anyone who was bummed bc they overpowered their boat...I have, though, come across people who were very bummed bc they underpowered their boat. Go with 300's IMO.

A few years ago I repowered a 20ft Radon from a 260hp 350 Mercruiser to a 350hp 383 Mercruiser. I burned less fuel and went faster with the more powerful motor.

 

[clevel]

It seems like you really need to have accurate information of what the fully dressed weight of your boat is. If the builder is offering 200 thru 300 hp twin engines, they should be able to help you in your decision. Does your builder, any of their dealers, or their buyers have a same model for sea trial? A sea trial should help you in figuring how long it took a particular engine size to get onto plane and the effort needed to push the boat.