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Old 26 June 2018, 18:51   #1
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zodiac 630 performance

I have finally gotten my zodiac 630 boat in the water. it is powered by 2 honda 90hp 4 strokes. I am finding that top speed on the boat with twin motors are about 40mph according to my phone gps. i was thinking i would see some more speed than that. i was topping out at 6000rpm so i believe it is propped correctly. With only 1 motor the boat ran pretty good with a top speed of 25mph. the boat had only 1 person and only 25 gallons of gas so not loaded by any means. I found that i needed to keep the motors trimmed way down and even on plane seemed like the bow was a little high rideing. I planned on keeping the twin motors but have heard and thought alot about the performance of switching to a single outboard. I want the comfort of haveing 2 motors to deliver me to safty on the ocean. I was just wondering if anyone had the same boat with twins and if 40mph is what i should expect. I was on a perfectly calm lake and realize that on the ocean i may never need to be going faster than 40. i just want to know if i should expect more.
I also own an avon 5.4 with mercury 90hp 2 stroke and it is still my favorite. there is nothing similar to the ride of thesetwo boats. the avon feels like a sports car on the water and the hurricane feels like a tank. any imput would be great, i will post some pics soon
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Old 28 June 2018, 07:34   #2
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I think 40 mph sounds about right. You probably wont get much more after tweaking height, trim, props, etc.

You will get more speed with a single. If you do a single 225 ish you'll probably get around 50mph.

Not worth sacrificing redundancy of twins. And you are lucky it planes on one motor!


Congrats on getting it in the water
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Old 28 June 2018, 09:43   #3
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pics

thought id share some pics of my boat. Thanks for the info. Believe it or not the boat planes pretty good with only one motor, top speed is 25. It jumps on plane without too much trouble, very please about that.
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Old 28 June 2018, 09:44   #4
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sorry pics didnt go through will try again later today
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Old 29 June 2018, 05:23   #5
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planing on one engine

Quote:
Originally Posted by learning to fly View Post
sorry pics didnt go through will try again later today
drool

I've had twin 4-strokes 20+ years .... never been able to plane with one though! :-(
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Old 29 June 2018, 07:08   #6
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I have 2 tohatsu 90 tldis’ on my 7.7 m rib. I used to get similar speeds as you. My rib doesn’t have the same top end speed anymore since I added 280 litres of fuel, cabin, Bimini and rocket launcher( rod holders). With 6 people on board I only get 28 kts 2 engines and 21 kts one engine. It still gets on the plane easily but top end speed has dropped off due to weight and extra windage. When I first tested my RIB which was a bare RIB with minimal safety gear and a small centre console I got 27 kts on one 90 tohatsu tldi I didn’t have the second engine at that stage.
RPM
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Old 29 June 2018, 08:47   #7
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I had the 550 (OK smaller and lighter) with single 90HP and could get about 35MPH. Mine was a tiny bit over propped as I could only hit 5500RPM, but not much different.

I think the rule of thumb for twins is double HP then subtract about 10-15% - so you've effectively got around 150/160HP. I would expect a little more out of that setup, but probably not much more. You could probably afford to increase 1 pitch size in prop if you are after top speed.
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Old 30 June 2018, 00:42   #8
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pics i hope they come through
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Old 01 July 2018, 17:23   #9
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Nice rig !
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Old 08 July 2018, 21:16   #10
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ok. I had a hard time believeing my speed because i was useing my phone, i have confirmed that i can only get about 39moh with both my botors. I am a little high with my revs. im getting asbout 6100 rpm mayby a little more. I have taken my props off and will bring them to a shop that has helped me in the past. Running a single outboard with the second out of the water i got 30mph briefly. Boat felt very smooth. I am only gaining 8 or 9 mph with the second motor. I believe i can feel the the extra drag when both motors are running . I am hopeing to pick up a few more mph by tweaking the props. Ill keep everyone informed. I am writeing this because i have always wondered what i wanted, My number 1 worry is safty. I feel so much better knowing i have an extra motor on the boat. I am beginning to think this is the only bennifit. Ive read all the auguments for and against. ive been told to " take those lumps of metal off and throw on a 150 or even 200" I am going to continue to tweak the boat and see just what i can get with it. I can tell u this though. I also own a searider 5.4 with a mercry 90hp and it is a thrill to drive. It feels like a sports car on the water. my hurricane feels like a jeep. It powers through stuff and it feels big and bulky in the water compared to the avon. then again the avon is about 1200 lbs loaded as compared to probally over 3500lbs. I have almost 900 lbs of motors on the back of the boat alone.
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Old 18 July 2018, 12:37   #11
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update

update on my boat. I had the props adjusted a bit. a shop chaanged the rake a bit and put a little cupping on the edges. i was told that i should get a couple more mph and that the prop would grab a lot better. i felt befor the props worked hard to get on plane. they sometimes sounded like they had come out of the water but they didnt, the rpms were consistant. with the new props I have actually lost a mile or 2 per hour. my boat is getting about 56 or 5700 rpm but i am extremely happy with the performance. the boat jumps right up on plane and sounds better doing it. it turnes pretty sharply without loseing grip. I was looking for more speed but am very happy with the difference now in performance. I may tweak the props a bit more to see if i can get my rpms up a couple hundred but i am thinking i may be expecting more speed than is capable with this setup. i will look into mayby lifting the motors up a hole next. I hope this helps anyone thinking of getting twins on a boat. for pure fun im sure id be happier with a single large outboard but i am stubborn and like haveing the protection of twins. Ive noticed that even when running with 1 motor i have lost a mile or two per hour. I am still happy that i can plane on 1 motor and get speeds overr 25mph.
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Old 18 July 2018, 17:44   #12
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Check with Honda and find out what the optimal RPM’s range is for those motors. My buddy has the same boat with a 150 etec on a bracket. I believe he tops out at 42 mph.
Getting close to finishing my 640 which is a heavier boat. Gonna run with a Yamaha F150 on that.
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