12 ft zodiak max hp

[woodsailboat]

Back in 85 my dad bought a 12 ft zodiak brand new and it said on the transom that max hp was 25 hp so since he had the money he figured he would get the max hp so he got a new 25hp merc 2 stroke and when he put it on the boat he found that at a little past half throttle the boat would actualy start to fold from the torque of the prop. He even tried a new thicker floor and adding extra weight but he still could not go past half throttle without it folding. So I guess my questions would be how do they test these things and why where they so far off from the right horse power.

 

[Sea Rider]

Re: 12 ft zodiak max hp

Is it an air mat floor ? If so, you need to have it inflated at least to 10 psi to achieve better floor rigidity, get a pressure gauge to be on the safe side and a pump that will reach that high pressure. Inflate sib's tubes and keel to at least 3.0 psi once resting for some minutes on water.

Other issue to keep in mind, sib should perform well with a 25 if you place max number of passengers stated on transom's plate. If boating with less passengers, simply back up throttle.

Have inflated large air mats sibs to 12 psi and find that no matter how hard they are inflated to still flexes a bit, it's sib portability against floor rigidity, can't have both at same time, it's the nature of any air floor beast.

Happy Boating

 

[Peter_C]

Re: 12 ft zodiak max hp

You have to have a gauge. I chased a weird problem with my boat and eventually got a gauge. I was running way to little pressure.

 

[woodsailboat]

Re: 12 ft zodiak max hp

He bought it back in 1985 long before I was born so we do not have it any more but he said that it had a 1/2" thick marine ply wood floor with an inflatable keel he said he pumped every thing up to where it was hard enough to sit on without it sinking down. A few years after he bought it he put a new 3/4" thick ply wood floor in it but it didnt make a difference.

 

[Pack Rat]

Re: 12 ft zodiak max hp

I had a Zodiac Mark II Compact 12.5' made in about 1979. The capacity plate rated it for a 40 HP and I used a Mariner 28 hp
2 stroke. It also had the plywood floor with the option for an aluminum floor. It was very solid. There are many posts you can find on this forum where individuals underinflate and have the flexing problem. If you had a pic of the interior it might reveal something. I'm wondering about the side stringers that attached to the floor boards?

 

[Sea Rider]

Re: 12 ft zodiak max hp

You can't sit on keel if underinflated along with tubes will contribute to have flex issues. To pump a sib hard enough is no indicative you have reach the factoty pressure recommendation to perform as expected, worst with max engine rated at transom. Had 2 Zodiacs and find that side stringers, the plastic ones that secured floorboards between each other produced hinge effect flexing a bit floor panels on choppy waters.

Happy Boating