Outboard Powered 330 SS
 

I have finally given the go ahead on the outboard conversion of my 330 SS.
I am sure there will be quite a few eyebrows raised on this one, but believe me I can not run inboards where i am.
Without going into detail , 33 feet boats can ONLY be moored in ocean salt water in humid temperatures and all year around.
There are hundreds of boats moored right next to each other so the electrolysis is rampant.
Fortunately , the very low cost of the transom/bracket work and electricall rigging work locally , allows me to sell the inboards and offset the cost of the transom and electrical work.
That leaves me now with the choice of outboards.
Not looking at beating the original speeds or winning offshore races, but hoping to be able to reach 50MPH or about with the OUTboards.
Now need to decide if it can be done with 2 x 250 verado's or if 2 x 300's are needed.
From my internet searches I have seen conflicting info of (hull extended bracketed) outboards versus inboard engines.

Anyone care to pitch in ?
All positive advise appreciated.

Thanks

Mike

I would go with the 300's, if you can swing it. This should be interesting to follow. I think I have seen a go-fast boat converted to outboards, but not a day boat, like the 330.

Post pics as you can.

Thanks Tpenfield , read a lot of your posts on the forums.
Project will start next month as boat is on the way now , will definitely post pics of project.

Mike- I would think you would want the 300s also, the 330 has about a 10' beam and less deadrise than a pure offshore boat. More power=better IMHO.

Thanks for input Glenn , looking at pricing of 300's and yamaha F350's , they should be the cheapest in the world here as they are made around here...

I know it's "stratosphere" thinking but a pair of "7" 557's would be very sweet on that boat !!!

Definitely 300's or 350's. Gotta see pics of this!!! Good luck!

The small stock engines made about 300 HP each, and probably would not easily hit 50mph. I too would try to put 300 HP outboards on the 330 over the 250s.

There is not enough omph with 2 300s to make that thing jump on plane and do 50.

i would go for triple 225 or 250 Yamahas and never look back.

my dad has a single 225 yamaha that is 13 years old and has a good 4000 hours on it but hard to tell because the hour meter quit years ago.

Had to put a new lower unit on it a few years ago because it lost a shaft seal from a fish line wrap.

I had to rebuild the exhaust but that was because of a bogus year of component manufacture.

But all in all the motors are relentlessly reliable and low maintenance.

I would never hang anything else on my outboard transom after my experience with them.


Wheer do you live?

I take it you are somewhere over in Europe

Highly doubt 300s will push that boat to 50mph easily. I agree with that weight trips are a much better option. Basing this on a 30 scarab sport which is a much lighter boat than a 330ss running at 60 on 300s. That boat is 4000 pounds heavier than the scarab based on a dry weight of 9700lbs. Maybe a set of the merc 400s would be ideal for that.

This is from a post in a different forum wich i saved, since I own a 330ss myself.
I dont know how to compare the efficency of the twin prop B3 to an out board or how the substancial weight reduction (with out boards) will improve performance.


" Dont know how accurate these numbers are but I found this card in the boat when I got it. its a 1998 330ss.
T-Merc 7.4L MPI Bravo III
RPM MPH GAL/HR RANGE MPG
1500 10 9 160 1.11
2000 18 13 199 1.38
2500 27 18 216 1.50
3000 35 23 219 1.52
3500 41 31 190 1.32
4000 48 43 161 1.12
4400 53 50 156 1.06

Actuallity, I also get about 35mph out of 3600rpm. Top up, probably 100 gal of fuel, full water, 100lb cooler, quessing about 500lbs of gear (canvas/floats/food/people/closet full of CR@P). Top end 50mph on gps with top down. These number on the card might be accurate if you stripped it down as they normally do when they publish performance reports. "

You might want to start with just checking in with some bracket manaufactures just so see what is requried. Also do a serach on this board for Bracket conversions. Good Luck and I think you might need Triples to get that thing up on plane. I also think the 330 swim platform would need to be modfied otherwise your props will be set way back from the transom. Also if you look at the new searay they hide the outboards insde the boat where the normal engine woudl sit you might look at this option. I always like a project but I am not sure if this is a good one for the money in my opion but good luck.

Thanks All ,

I am based in Hong Kong.
Dry stacking is at a premium here , cheapest one now on second hand market is USD 200K at a fancy marina.
Max boat length at any dry stack in Hong Kong is 28 feet.
As for Swing moorings , there are about 8000 licensed vessels without a legal mooring , hence all the popular bays are filled to the brim with moorings , you might be able to feel the electrolysis when you stick your hand in the water.
Not to mention the very high salt levels and even higher humidity here in summer.
I am the lucky owner of a dry stack but again limited at 28 feet , this was the reason why i originally looked at 280 SS , but based on forum reading the 330 offers that much more comfort and comes out on top for party boating.
I feel any larger SS would not be feasible to convert to outboards.
I am no engineer but i still don't get the sterndrive versus outboard HP comparison.
As rightly stated in some posts , the original boat has 2 x 320 Volvo Penta's for a total of 640 HP and weigh a couple of hundred LBS more than 2 x 300 outboards I would imagine.
I get the torque thing of sterndrives but don't understand why 2 x 300's (or 2 x F350 v8 outboards) would not get the 330 running like it did with the sterndrives.
I will look at costing and feasibility of adding triple 250's , if that weight can be accommodated by te local guys that did the other conversions here , perhaps thats what needs to be done.
Was hoping cost and weight wise that 2 x 300's would do it though....
I will be out at the bay tomorrow and will take some shots of the conversions done (6-8 years ago) , couple have been done on a euro transom whereby they simple use the swim platform and built additional fiberglass underneath and extend hull.

Starting to think the 280 may have been an easier option....

Thanks all ,

mike

Would this be any kind of indication what to expect on the 330 ?

http://www.boattest.com/Partners/Par...id=1778&p=0&s=

some data from grady white with different set ups :

http://www.gradywhite.com/330/performance_data/1

Good luck with the conversion. It will definitely be a "one of a kind" and probably won't be duplicated. I don't think your going to be able to compare it to anything. A 330 wasn't designed to be ran with outboard power, not saying it can't be done. Boats like the Grady White in the boat test video were built and designed for outboards. Now I'm no boat builder but I'd think that there are differences in design and calculations when building a boat with inboards vs outboards. I don't see too many brands that have inboards or outboards as power options.

You say max length for the dry stack is 28 feet, assuming you mean what you say, how will you dry stack a boat 5 feet longer than the maximum allowance? Just have to pay someone to look the other way?

maine , well that is sort of the point of the conversion.
As 28 is the limit , a 33 feet boat will have to be swing moored.
Don't need to do a conversion on a 280 SS.

Thanks for input split decision , I am no boat builder either but the 330SS is lighter and I believe has better hull.

Ahhh, okay, I see now. I don't think that will be an easy project because of the existing integrated swim platform, but anything can be done I guess, although I think most people would say sell the 330ss and buy the grady with outboards already on it. The balance and ride may be affected too.

For a comparison, I had a friend convert a 24 grady style with a 205 horse 4.3 sterndrive to a 200 horse yahmaha. The outboard was 2mph slower, so pretty close. This was an easier conversion though, as it had a square transom and they bolted an outboard brackett to it and he gained interior space.

Got a buddy with a 330 SS with twin 350 MAG MPIs (300 HP) and it does just fine. As stated above, not sure what the difference will be with the different weight distribution, Bravo III's vs. outboard lower unit, etc.

Thanks Maine , perhaps i wasn't to clear about that.
Again , I am no boat engineer , but from what I understand Formula hulls are highly regarded and in comparison with a Grady should have a better performance , even with outboards.
The reason i am going this route is that the Formula 330SS exactly fits my specs , I have had whalers and recently malibu's including the 24 LSV , its just not worth it on the ocean and now shifting to a nice party boat with some overnight amenities.
Really have looked at other boats , including the outboard power concept sport , there just isn't anything unless i go opposite of sporty and go Jeanneau Cap Camarat , not quite ready for that.
I guess i will be the first one converting a 330 SS , either way I will set a precedent...

Thank for your input.

Thanks knot 4 me , I know the 330 SS does just fine with sterndrives , but thats the point.
I can't keep them alive as described in my original post , due to having to be in salt water , humid conditions all year around.
I am just crazy about the 330 SS and I think its the maximum sized SS that can be converted and kept alive in salt water all year around.

Just my 2 cents worth........

Great idea, fully understand your position about outboards Vs. sterndrives for where you live. I think you will need more than 250 X 2 to get the big boat moving. 350's or the new 400's would be ideal but the cost may well blow out off the map. I think 300's would come close to achieving the desired result. There's plenty of decent Centre Consoles close to 10,000 lbs that will do 60 with twin 300's so I don't think 50 is out of the question given the extra weight and beam.

I presume you'll have to antifoul? Better keep your bottom spotless!!

Not a big fan of a bracket on something that size. I can imagine cutting the platform in the centre and mounting engines on the (re-designed) transom in a conventional manner. You'd end up with small integrated swim platforms on either side of your outboards.

Good luck whichever way you go, a bit project and I'd love to see pics...!!

RR

P.S. Check the sea Ray 370 Venture. http://www.boattest.com/boats/boat_video.aspx?ID=2752
A whopping 16,700 lbs as tested and 43.7 mph. True it's the latest design and all that but still a big heavy boat. MMmmm

Suzuki 300s are the best deal going.

250s would be risky imo. My boat is Jefferson marlago 35 and goes 53mph light load with 250s. But it's only 7600ish dry with the engines.

Since you're having a science experiment, ering on the side of extra power would be wise. 300hp zukes cost the same as 250s anyways.

I actually wouldn't even attempt the whole project but I'd really like to see how it turns out.

They only made this boat for a year or two......production has stopped.

Don't think your going to be happy with the results either

Production has stopped? Sure?
I'm not well informed but according to their website, the Venture is still a current boat in 2015. Would be a shame if production has ceased. Sea Ray haven't built many 'mistakes'. http://global.searay.com/page.aspx/p...0-Venture.aspx

RR

I'd venture to say that you will run into issues on acceleration and planing due to the reduction in torque and the much smaller blade area compared to the B3s. And the CG on the hull is going to be significant altered. Might want to give Formula a call, they might have some input.

My Nor-Tech 34 CC reportedly weighs in dry at 9K lbs. With twin 300s it runs low 60s with plenty of fuel, factory ran it 65.9 on test run, but we know it had little fuel or extra weight. With a full tanks, 270 gallons of gas, the key to getting it on plane is to have patients, it certainly is not a quick process. I know I'm comparing a boat engineered for outboards to a boat engineered for stern drives, but both boats are similar in size, weight and beam (10 ft).

Any update on this project?

I am very interested in seeing how it turns out.

Outboard Powered 330 SS
 

Did this project ever come to reality?
Im also thinking about it in my 280 ss and Formula now is selling with outboards

I made the jump for outboards, transom holes closed this Saturday, bracket will be installed Monday and by the end of next week I will be running a pair of Zukes 300. Couldnt deal anymore with upside down maintenance.
https://cimg4.ibsrv.net/gimg/www.off...82a319d4b9.jpg
https://cimg7.ibsrv.net/gimg/www.off...ab7bd29de3.jpg

We need to see a build thread on this.

Transom sealed
https://cimg3.ibsrv.net/gimg/www.off...4181868300.jpg

Coming right along! Since this is a 280, twin 300's should be nice. The OP's boat was a 330 and not sure if twin 300's would be adequate.

330s came with 330hp 454s, 310hp 454s, and even 350s which I’m guessing were around 300hp.

Mine runs 58 with 330s. It will run great with 300s.

Mine had twin 5.0 mpi (260 hp each), wot was 50mph.

You might be right but I have my doubts on 300 OB's on a 330. It's not all about HP, your 454's will have waaaayy more torque not to mention more bite with duo-prop I/O's.

The smallest OB engines Formula offers on their 310 Sun Sport is twin 350 Verados.

They won’t have as much bite as B3s, but zukes have very big wheels on them.

OBs tend to run better HP for HP due to either the cg being further back and or the X dimension being better.

I also have a 35’ CC with twin Suzuki 250s that runs 52.

Been talking about doing this to a friend of mines 06 330ss. What is the plan for the space/abandoned engine compartment? Leave as is/storage?

Hot tub