Islander W/F350??

[CJBROWN]

There are a few Islanders for sale around the country with the old 2-smokers on them. What if I bought one, sold off the motor and had a new F350 put on there. Whaddya think, would that work?

Yeah, I know off-shore guys like the redundency of twins, but one motor is so much simpler, less maintenance, less gas, less headache. Besides, I don't get more than 50 miles offshore anyway.

Looks like they offer a 30" shaft, weighs in at 822lbs. If twin 150's weigh about 950, why wouldn't the 350 be just dandy?

 

[gw204]

I think it's more complicated than just the total engine weight. It also involves how that weight is distributed. With twins, it's spread out. Not the case with a single.

However, there are many other options in the single 300 HP (much lighter) range that should be fine.

300 Opti
300 Verado
300 Suzuki
300 HPDI...run Forrest run.

A quick call to Grady Customer Service would confirm this though.

 

[nevsatII]

You also have to consider the extra torque on the hull, and you might not have room to completely tilt the engine up. The cowling on that v8 is very tall, I know Gulfstreams with the 350s on them have a longer engine bracket to allow for clearance.

 

[Tashmoo]

I have the F350 on a 275 Tournament which, I am told is built on the Islander Hull. It performs very well and consistent with the posted F350 performance data for the Tournament 275 on the GW web site. The problem as I have been told is that the transom hade to be modified in order to handle the increased torque of the F350. Even if the transom is rated up to 500 hp it does not mean that it can handle a single center line of torque exerted by one 350 hp engine. Keep in mind the boat was in all likelihood originally designed for one 250 maybe a 300 hp on a single centerline. In the end the answer will come by checking with GW.

I completely agree with your premise, why have two when it can be done just as well or maybe better with one! The Tournament 275/F350 performance from my research is better then with 2x150's and equal to or a little less than 2x200's at thousands of $$$$ less. And yes if you're really going 100 miles off shore I agree you can't have enough engines on the back.

 

[Legend]

I wanted to repower a 2004 Gulfstream with a 350 and the dealer told me GW soes not recommend it because of the added torque stress the engine would put on the hull. The boat is rated for 400HP. 350 is a different animal. I was told it actually runs quieter and smoother than the 225F I currently have. Guess the hulls were reinforced for this model year since many are equiped with the 350. I saw one at the boat show in Boston last weekend. It is a monster engine

 

[BobP]

If you didn't care about tilt range, can probably plate the transom both sides to take care of what Brian mentioned. 1/2 in. stainless plate twice as wide as engine, ought to spead the forces out well enough.

I doubt Grady HQ will offer advise on this, so you will be on your own.
And don't drop the 1/2 in. plates on your feet !

If you want a bigger boat, why not look at bracketed old Sailfish model or Gulftstream, replace bracket with new single rated for F350, since hulls are good for 400HP. The bracket will spread out the forces, as it does now. May get full tilt range as a bonus.

 

[Grog]

I doubt you will have enough room to swing the big V8 up. If you get an Islander with running "smokers" why dump them? $20+K buys A LOT of gas. Twins give you redundancy and much better manuverability. If you want, drop on a pair of F150's and get better milage.

 

[BobP]

Legend, that's interesting what Grady (sales) told you about torque forces.
Did you let it go at that ?

It would make sense if the Gulf rated for twin 200s with the bracket mandated counter-rotators, then the torque would be nulled before it reached the transom. Is there such a requirement by Grady? Can one install twin 200s of same rotation ? Plenty of torque going on vs. having one F350.

My boat namplate doesn't call for counters to comply with the 400 HP.

 

[Legend]

BobP - I did not pursue any further - I thought it was strange that it could handle twin 200 but not the 350. It would have been the perfect solution to the underpower situation I am dealing with with a single F225. Most case it is enough to get by, however a full boat and heavy seas it can be a struggle to keep it on plane.

 

[Brad1]

http://www.gradywhite.com/grady-built/structure.php3

From the Grady White website:

Super Strong Transoms
Two 3/4" layers and one 3/8" layer of plywood are fiberglass laminated together and braced with a 5/16" angled aluminum brace to make our super strong laminated transoms. The brace supports the top motor hole mounts, transmitting torque throughout the transom instead of around the bolt holes as in other boats.

In the GW dealerships they have a display case which shows a sample of some of their construction techniques, one of which being the transom core (a cross section showing the 5/16" angle is integrated into the tranom core). I don't think they've always built them this way, but they supposedly have as early as '03 (the model year of my GW). I saw a mid-80s Offshore getting it's transom core removed and I didn't see the 5/16" angle on it. So I think it's something new. Don't confuse this with that flimsy aluminum angle trim where the hull meets the liner. The 5/16" angle is internal.

But even if the transom is stout enough to handle the extra weight and torque of the engine, you still need to take into consideration how much lower the boat is going to sit lower in the stern due to the added weight.

By the way, I can't see where that 5/16" piece of aluminum is going to do any good if the transom were rotten.

 

[BobP]

Gotta luv salesmen, that's another story.

Unfortunately, Yamaha is not going to be much help to you, as Grady wasn't, in my opinion, unless you "upgrade".

The F350 is a whopping 800 lbs with a whopping $$ price tag to boot.

Don't expect the following advise from Grady -
------------------------------

Suzuki to the rescue !!

The 300 Zuk is lighter by 200 lbs, fits the same transom drillings, does require conversion - though there are very good "repowering" deals at the Zuk dealers incl. the long warranties.

Over at THT, I don't recall seeing any complaints with the Zuk 4 strokers.

If you are not so inclined to stay with Yamaha, I think the Zuk 300 will make a considerable enough impact on performance in a single package to make it worth the while.

When I repowered my twin 200 Johnson smoke screens, the Zuk 175 was a very close contender, the only other engine I would have repowered with.

 

[CJBROWN]

>snip
But even if the transom is stout enough to handle the extra weight and torque of the engine, you still need to take into consideration how much lower the boat is going to sit lower in the stern due to the added weight.

>snip

What 'added weight"?

If the Ilsander is rated for 500hp, single or twins, then it's designed for engine weight of around 900lbs (twin F200's = >1000lbs). If the F350 is 822lbs, why is that 'added weight'? Why would it sit lower than a pair of 200's?

I don't really get the torque thing either. So it torques a little more than a 250, how would that be any more stress on the transom? You guys don't think the transom is strong enough to handle one motor, but it is for twin 250's? That doesn't make sense to me either.

How tall the engine is may make some sense, I'd have to look at the design back there. On my 208 it wouldn't matter how tall it was, it would still hang over the front of the well.

The Zook 300 makes good sense too, probably an even better alternative to the F350.

As far as 'why would I replace an old two-stroke', well that's easy - they are stinky, noisy, they smoke a lot, and they suck a LOT of gas. If I can buy a good example of a boat for around $40K, maybe even a little less, sell the old motor for a couple of grand, and spend $20K on a new 4-stroke, then I'm in for under $60K with a nice 27' trailerable with a new motor. So far I haven't found a Sailfish in that price range that has four-strokes. And they're quite a bit bigger on a trailer. Frankly I'd rather have a Sailfish, but it's probably not the best choice if I want to do much trailering. Oh, and I'm not into brackets, I'll stay with a transom mounted engine thank you :wink:

Thanks for all of the replies!

 

[Brad1]

>snip
But even if the transom is stout enough to handle the extra weight and torque of the engine, you still need to take into consideration how much lower the boat is going to sit lower in the stern due to the added weight.

>snip

What 'added weight"?

If the Ilsander is rated for 500hp, single or twins, then it's designed for engine weight of around 900lbs (twin F200's = >1000lbs). If the F350 is 822lbs, why is that 'added weight'? Why would it sit lower than a pair of 200's?

Yeah, your right. Sorry about that.

 

[ocnslr]

We purchased our 2002 Islander new with a 2001 Yamaha 250HP OX66. In October 2005, after 465 hours (with no problems) we repowered with twin F150s. We did it for the significant improvement in fuel economy, so we could safely run offshore on the single 150gal fuel supply.

Boat certainly sits lower, but scuppers well above the water.

Considered a Yamaha 300HPDI and the 300HP Suzuki. Also considered the twin 175 Suzukis, but they were not yet available to the dealers.

The Islander is great with twin F150s. I'm sure the performance would be fine with the F350, and some Islanders have twin F225s, so weight really isn't the issue.

While I can't address the torque from that big, single F350, I can say that there is no way that beast will tilt up in that eurotransom. And since I wouldn't have an engine that couldn't clear the water, then the F350 wouldn't be for me.

Might be fine if not kept in the water, but what about when you need to tilt it up to get the fishing line off.... and yes, that does happen....

Brian

 

[HDGWJOE]

I doubt you will have enough room to swing the big V8 up. .

Excellent point.. you might want to get this question answered first!!! Everything else may be a moot point.

 

[HDGWJOE]

OCNSLR: "While I can't address the torque from that big, single F350, I can say that there is no way that beast will tilt up in that eurotransom. And since I wouldn't have an engine that couldn't clear the water, then the F350 wouldn't be for me. "


sorry Brian... missed your post.

 

[gradyfish22]

I would not go with an F350. Pretty sure that transom cannot support the torque. Newer models may be the same hull but most likely have a beefed up transom that can support the weight and torque. Also, there is a connection between the transom and stringers so the force from the motor is applied evenly to the hull, this may have been altered as well. This means above the water you may not see changes. I also think manuverability would be better with twins. Grady White can tell you exactly what weight and HP, along with engines they think are suitable for that model and year. If they do not recommend it, DO NOT do it!!! There is a reason for that. I work as a Naval Architect and design boats. Your transom is designed to support a certain load and torque, and has a certain amount of factor of safety. As the transom ages, and the boat gets used, this factor of safety goes down. If you are over powered or have too much torque, it will be worse and will become dangerous. As for F350's...I think they are going to been seen on new boats only. There are probably only a handful of newer boats that were designed for four strokes, that will be able to handle an F350 as a repower.

 

[CJBROWN]

Seems a pair of F150's or suzuki 175's would be the best bet. Probably similar money too, maybe just a tad more. I can say my single F150 is sure easy to live with, clean, quiet, sips fuel, and easy to maintain.

Good points made here, thanks for everyone's input on it. I learned things I hadn't thought of, and got to know the layout better on the Islander. I would like to see one in person sometime, even better - compare one to a Sailfish side-by-side. I guess the latter won out on that battle at the factory.

Did somebody mention they actually called the factory on this subject?

 

[Legend]

Chris - I did not speak directly to the Factory. I did speak with a GW dealer and they told me GW advises against repowering an 04 Gulfstream with the 350 for the torque reasons mentioned previously.