Determining Shaft length on a Zodiac FC470

F470 · 06 June 2013, 22:17

I have a Zodiac FC470 and I have measured the transom in order to determine the shaft length needed for the motor I will be purchasing. I have measured top of transom down to the bottom of the transom where it meetings the flooring, on the center. The distance is 18.5" (47cm) which should put me in the long category according to this site. Can other FC/F470 owners confirm if this seems accurate and reasonable? Thanks!

Nos4r2 · 06 June 2013, 22:28

That site's wrong. 'Short' shaft is a bit variable depending on how big the motor is.

You need an 18" shaft.

F470 · 06 June 2013, 22:33

Glad I asked. Is that considered long? Is there a better website to explain this with more accurate information?

Nos4r2 · 06 June 2013, 22:40

Someone correct me if I'm wrong please! This is as far as I know:-

It's usually considered a short shaft on bigger motors.

As far as I know, what you have is...

15"-ultra short/extra short

18"-short shaft

20"ish-longshaft

25"-XL shaft

30"-XXL shaft.

On smaller motors-the sort of thing used on a dinghy or to power a small daysailer/yacht you see short shaft (for dinghies) which is about 15", or longshaft which is 20-21"

Tim M · 06 June 2013, 22:55

Long Shaft Outboards and Short Shaft Outboard Motors

captnjack · 06 June 2013, 22:59

Quote:

Originally Posted by F470

I have measured top of transom down to the bottom of the transom where it meetings the flooring, on the center.

Can't tell from what you've written but you should be measuring on the outside of the transom. Top all the way down to the lowest, deepest part of the V.

It should be a "long" or 20" shaft however:
Technical Specifications

martini · 06 June 2013, 23:46

Quote:

Originally Posted by Nos4r2

Someone correct me if I'm wrong please! This is as far as I know:-

It's usually considered a short shaft on bigger motors.

As far as I know, what you have is...

15"-ultra short/extra short

18"-short shaft

20"ish-longshaft

25"-XL shaft

30"-XXL shaft.

On smaller motors-the sort of thing used on a dinghy or to power a small daysailer/yacht you see short shaft (for dinghies) which is about 15", or longshaft which is 20-21"

I've always understood it to be 15" short shaft, 20" long shaft, 25" XL, 30" XXL.

OP - Fc470's are long shaft as standard but can be specced for a shaft. Mine is short shaft, next time I'm at my shed ill stick a tape measure on it

Nos4r2 · 07 June 2013, 00:03

Quote:

Originally Posted by martini

I've always understood it to be 15" short shaft, 20" long shaft, 25" XL, 30" XXL.

OP - Fc470's are long shaft as standard but can be specced for a shaft. Mine is short shaft, next time I'm at my shed ill stick a tape measure on it

I thought that too, but there seems to be the odd 18" shaft cropping up, and I keep seeing 15" shaft big motors (200hp+) described as ultra short.

It might be what the link Tim M posted up says as 18" true length.

F470 · 07 June 2013, 03:35

Thanks! Please do. What are we measuring here exactly anyway and why? Are wee assuring the transom height or transom to keel? I have speed tubes on mine so that has to be considered I have been told but not sure why?

Quote:

Originally Posted by martini

OP - Fc470's are long shaft as standard but can be specced for a shaft. Mine is short shaft, next time I'm at my shed ill stick a tape measure on it

captnjack · 11 June 2013, 18:04

Top of transom to bottom of keel on the outside. Right in the middle of the transom. Don't worry about the speed tubes they don't dictate the engine shaft length. It should end up measuring about 19.5" or so.

Where did you find a FC470 in the PNW? Never seen one her in person so if you ever get up to Puget Sound let me know and we can go for a spin.

cgoing · 11 June 2013, 20:38

The newer F 470's have an 18" transom by design. Older ones had a 15" shaft. The newer ones are designed for use with a 20" shaft motor. The explanation I was given was it is designed with a shorter transom to keep the motor lower in the water and less likely to have the prop come out of the water and make noise during beach landing. To me at least that makes sense when you consider that these boats are designed for the military and not the rest of us inflatable addicts that enjoy using them in their after life.

-C

martini · 12 June 2013, 19:01

Quote:

Originally Posted by F470

Thanks! Please do. What are we measuring here exactly anyway and why? Are wee assuring the transom height or transom to keel? I have speed tubes on mine so that has to be considered I have been told but not sure why?

My transom measures 15" in height on its centre line. It was ordered from the factory as a short shaft model.

Sent from my portable speaking device using Rib.net

Squid Boat · 12 June 2013, 19:13

Quote:

Originally Posted by martini

My transom measures 15" in height on its centre line. It was ordered from the factory as a short shaft model.

Sent from my portable speaking device using Rib.net

That is the same as my Avon CRRC 4.5 as well.

Cheers, Squid

captnjack · 12 June 2013, 19:17

Quote:

Originally Posted by martini

My transom measures 15" in height on its centre line. It was ordered from the factory as a short shaft model.

Its a royal pita to find anything larger than 25hp with a 15" shaft over here. Almost for sure a special order or a franken motor.

martini · 12 June 2013, 22:55

Quote:

Originally Posted by captnjack

Its a royal pita to find anything larger than 25hp with a 15" shaft over here. Almost for sure a special order or a franken motor.

Mines a Mariner 50, no problems at all. I'm surprised buying new would be a problem, 2nd hand market is only going to be whats in popular use.

F470 · 12 June 2013, 23:30

Mine measured 18.5" top to bottom centered. It's actually an FC470 and its a 2004 model. Thanks for the explanation.

Quote:

Originally Posted by cgoing

The newer F 470's have an 18" transom by design. Older ones had a 15" shaft. The newer ones are designed for use with a 20" shaft motor. The explanation I was given was it is designed with a shorter transom to keep the motor lower in the water and less likely to have the prop come out of the water and make noise during beach landing. To me at least that makes sense when you consider that these boats are designed for the military and not the rest of us inflatable addicts that enjoy using them in their after life.

-C

F470 · 12 June 2013, 23:33

It's from CA. I am in Gig Harbor from time to time so I'll let you know when I take the boat up there.

Quote:

Originally Posted by captnjack

Top of transom to bottom of keel on the outside. Right in the middle of the transom. Don't worry about the speed tubes they don't dictate the engine shaft length. It should end up measuring about 19.5" or so.

Where did you find a FC470 in the PNW? Never seen one her in person so if you ever get up to Puget Sound let me know and we can go for a spin.

captnjack · 19 June 2013, 19:57

Quote:

Originally Posted by martini

Mines a Mariner 50, no problems at all. I'm surprised buying new would be a problem, 2nd hand market is only going to be whats in popular use.

There are very very few North American boat manufacturers making boats for >25hp engines in anything but a long shaft (20"). You can special order a short (15") shaft 30, 40 or 50hp but its resale value is pathetic since so few boats rated for these midsized engines are built for them. I don't know why just seems to be convention.

Quote:

Originally Posted by F470

Mine measured 18.5" top to bottom centered. It's actually an FC470 and its a 2004 model. Thanks for the explanation.

Lucky you, a 20" will be easy to find new or used.

Quote:

Originally Posted by F470

It's from CA. I am in Gig Harbor from time to time so I'll let you know when I take the boat up there.

Cool, I am maybe 20mins north near Southworth. Love to see the boat and happy to bring mine along for show and tell.

GrantG · 16 July 2013, 23:00

Quote:

Originally Posted by captnjack

Its a royal pita to find anything larger than 25hp with a 15" shaft over here. Almost for sure a special order or a franken motor.

It sure is hard to find a short shaft in anything larger than 25 hp! I've been scanning Craigslist for a while now, and finally lucked out. Today I bought a 35 hp short shaft tiller in Tukwila for my FC470. I really wanted a 40 hp, but I was excited to find the proper shaft and control configuration in 35 hp.

captnjack · 16 July 2013, 23:28

Quote:

Originally Posted by GrantG

It sure is hard to find a short shaft in anything larger than 25 hp! I've been scanning Craigslist for a while now, and finally lucked out. Today I bought a 35 hp short shaft tiller in Tukwila for my FC470. I really wanted a 40 hp, but I was excited to find the proper shaft and control configuration in 35 hp.

Good news, Curious to see her all rigged out. And I have few people with inflatables to buddy boat with.