Zodiac 470 first run problems

Mrbacklash · 03 December 2017, 01:34

Ran my f470 today for the first time and had a couple issues with the bow wanting to dive. A little background about it is that the speed tubes have been removed because the previous owner filled them with foam for some reason. And I do not have an inflatable keel yet. The bow kept wanting to stay down when I applied power it is a 15 johnson 2 stroke. I had it inflated to about 2.5psi would that be the issue or is it more so the lack of keel?

Mrbacklash · 03 December 2017, 03:12

Also tried the engine at a couple different trim angles and it didn’t seem to help

Mikefule · 03 December 2017, 08:47

The keel does two important jobs: it helps with rigidity, and it creates the correct underwater profile. Without a keel, the boat will be less rigid and the wrong shape. The chance of getting it to plane is slim, and will rely on brute force and careful weight distribution if it is to work at all. Then it may not be safe.

On my first ever SIB, I lost the inflatable keel when packing away on the beach after a long day. Next time I used the boat, I put extra air in the tubes for rigidity. I managed to get it more or less on the plane but then, with no keel to keep everything in place, the front two floorboards came out of position and slid under the 3rd board.

You either need to find a new keel or find some way of improvising with something light and about the same shape. Good luck.

spartacus · 03 December 2017, 11:50

Should be easy enough to retrofit an inflatable keel. The part simply can be glued to inside of the keel at two locations at the transom and where the valve is near the bow. Don't glue the entire length. What's the floor made of, aluminium floorboards or marine ply? With the tubes and keel tube inflated to correct PSI, then the stringers that hold the floor in place lock into position to give the boat rigidity.

Useful link: http://www.rib.net/forum/f50/zodiac-...eel-74668.html

Defender keels here: https://www.defender.com/category.js...895&id=2345896

Squid Boat · 03 December 2017, 13:49

When you find a keel it can be fitted with 3 large pads of Mil spec Velcro at bow, center and stern. This way sand and debris can be cleaned out as needed.

Cheers

cgoing · 03 December 2017, 15:32

Need to run at a higher pressure should be around 3.2 psi. Do you still have the speed tube sheathes on the boat or are those removed to? Those full of water would certainly hurt performance as well.

Mrbacklash · 03 December 2017, 21:26

Ok thanks for confirming my suspicions I will give it a shot at 3.2 psi and order the keel I assume the 345 cm on defender will work? Doesn’t matter where the fill port is I will drill a hole to match. I completely removed the speed tubes

cgoing · 03 December 2017, 22:45

You should very location of the keel valve and other dims. Diameter will make a difference too

I may have a used keel for a 470.

Mrbacklash · 04 December 2017, 03:44

Quote:

Originally Posted by cgoing

You should very location of the keel valve and other dims. Diameter will make a difference too

I may have a used keel for a 470.

Let me know what you want for it

Mrbacklash · 17 March 2018, 18:23

Ok so yesterday it was a beautiful day and was able to run the boat with the keel and tubes aired up to 3.4 psi and what a difference it makes! with me (230lbs) safety gear and 2 gallons of gas i was able to hold a constant 20mph with the 2 stroke 15hp johnson and a 9.25x10 3 blade. I was still only able to run with the engine tucked all the way in if I changed the trim pin to lift the bow by one pin hole it starts to plane then the prop blows out. Thinking about changing it to a 9.25x10 4 blade the engine has plenty of top end rpm left it sounds like so if it drops 500 rpm it wont be an issue. Or i could go with a 9.25x11 3 blade any ideas? The 4 blade will definately help with the prop blowing out as well as hole shot with a heavier hunting load.

office888 · 17 March 2018, 20:04

Is your outboard the correct shaft size?

Most F470s take a long shaft.

Mrbacklash · 17 March 2018, 20:32

This is an old one it is a 15" transom

office888 · 17 March 2018, 21:12

Quote:

Originally Posted by Mrbacklash

This is an old one it is a 15" transom

Pic? My 1990 was a long shaft.

beamishken · 17 March 2018, 22:03

Assuming the shaft length is correct id say your heading in the wrong direction by increasing pitch. Its more likely to be ventilating because of too much pitch rather than too little. need to check with a tach to be sure, a 15 on a 4.7 is unlikely to be on the upper side of the available prop sizes

Mrbacklash · 17 March 2018, 22:16

Ok I will get a tiny tach and see what it says with it trimmed all the way in it sounds like it is definitely hitting the upper end of the rpm range but I will check and go from there. Thanks for the info

Mrbacklash · 17 March 2018, 23:54

It is a 1986 which is very old for a zodiac but it has had the luxury of living in Southeast Alaska where the sun does not shine much. I will get some better pics when I get back in town. I contemplated changing the transom height to 20 when I rebuilt the transom but decided against it. Holding out for an old 2stroke 25 yamaha.

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Mrbacklash · 17 March 2018, 23:59

Also really not sure what the model is, if it is a grand raid, futura or what if anyone has any ideas let me know

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office888 · 19 March 2018, 12:34

Quote:

Originally Posted by Mrbacklash

Also really not sure what the model is, if it is a grand raid, futura or what if anyone has any ideas let me know
Attachment 123832

It's a Futura Mark III, series 3636.

office888 · 19 March 2018, 12:42

Quote:

Originally Posted by Mrbacklash

It is a 1986 which is very old for a zodiac but it has had the luxury of living in Southeast Alaska where the sun does not shine much. I will get some better pics when I get back in town. I contemplated changing the transom height to 20 when I rebuilt the transom but decided against it. Holding out for an old 2stroke 25 yamaha.

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It appears to be a shortshaft.

The cavitation plate should be about 1 inch below the lowest point of the transom.

FanOfZHT · 19 March 2018, 18:52

Quote:

Originally Posted by office888

It's a Futura Mark III, series 3636.

Serie 3636 might be a combination of Hypalon and PVC. Early Futura boats, from Zodiac's recreational division, played with PVC fabric for a few years before making a complete change to PVC (Strongan) fabrics. Milpro's Futura hulls (F/FC and HD) only used Hypalon (CSM) fabrics until recently.
About 8 years ago the US Navy (incl. USMC) rebid the supply contract and required polyurethane fabric, so today Zodiac Milpro offers the F470 in both "PU" or CSM. (BTW, Wing Infl. won the contract and today is the primary supplier of the current CRRC (combat rubber raiding craft).