15 HP Yamaha

[Crestliner]

Picked up my new Crestliner a few weeks back and I have an issue with top end speed that you folks may be able to assist me with. The hull is a 14 foot Sportsman (14'7" x 76" beam) open tiller and weighs in at approx. 430 lbs.. The engine is approx. 110 lbs.. Add another 100 lbs. of gear plus two average adult fishermen. Max. load is probably now about 650 - 700 lbs.. (I mainly fish the Quabbin, which is why I limited the HP to comply with regs.) The issue I have is that I see many larger boats - some with downriggers - being pushed by 20 HP's up there & they are going past me with no problem. My boat is smaller, definitely weighs less and only 5 HP less that the max. allowed up there. My thinking is that the stock prop (an 11" pitch) is probably for light to regular loads. My rig is probably in the heavy load range, so I'm going to be trying out a 9" pitch prop next week (which the marina is letting me try out - if the rain ever stops!). My question: is this the correct path to take? Anything else I should be considering? Thanks for any help.

[Tuc]

I agree with the switch in props.Keep in mind that the diff in hp 25%. Also some of those guys are runing 25Hp 4 strokes which is more like 55% more.

[Angler Tangler]

You can also check to see that your throttle adjustment goes all the way to the stopper when the tiller handle is turned to wide open. If the throttle adjustment is off then your tiller may not be allowing you to open up all the way.

[Crestliner]

Thinking more about this; yes, I agree that I'm operating at a 25% dissadvantage as far as top end speed is concerned, BUT some of the boats being pushed up there with their 20's (I see very few 25's and I spend a lot of time up there) are "substancially" larger than my 14 footer. I've seen a coupld of 17' or 18' rigs with console steering, windshields and downriggers onboard moving along quite nicely. Something just doesn't add up in my mind. Maybe they do use the 25 4-strokes. They certainly are pushing a lot more weight than I am....that's a certainty. I probably need to talk to a couple of the regulars and see what they say(?). Anyway, I am going to try the prop pitch change and I'll certainly check that throttle control as well. Thanks again :)

[dwf52]

some of those "20s" are bigger motors with 20 horse markings. Have to admit I did that years ago, was really a 35 horse

[arlow]

Crestliner,

Do you have one of the hydrofoil fins you bolt to the lower unit? They can make a big difference. Get more of the hull out of the water and you gain speed. It makes a big difference in my 17 ft tracker with a 20 on it. I also try to keep only essentials on board when I go there to keep the weight down. Anything I dont absolutly need comes off the boat. every little bit helps.

[Toad]

Is the motor trimmed (tilted) properly to the boat. It would seem to me that the rig your describing should be able to just get up on plane. You may be too much bow up or bow down which, in either case would definitely cut your speed.

[Crestliner]

Thanks for the great suggestions folks; I have switched from an 11" prop to a 9" prop and it seems to have made a world of difference! From my X135 my speed with the 11" prop was between 14 and 16 mph. Now it's between 18 and 20 mph. A considerable performance increase. My trim on the engine is all the way down, so I may try raising it a notch or two and see what that does. I've had both batteries installed forward - one mid-ship and one in the bow to better distribute the weight. It still seems to take awhile to get her up on plane, so I may try a hydrofin as "arlow" suggested? Just hate to drill holes in the plate without knowing if it's going to be a plus or not. Can't go back once it's done! So, I'm still thinking about this one. Again....THANKS a bunch folks :)

[Crestliner]

Tried Toad's advice as well today....raising the trim a notch. Increased the top end to 22 mph. Thanks Toad :)

[Toad]

Glad it worked out for you. I have seen many boats improperly trimmed for best performance. It not only robs you of speed but it also increases your gas usage.

[YOTE BUSTER]

Put the hydrofin on it. you won't regret it i have one on my boat and i get on plane faster and can back off on the gas and still stay on plane.