Old Issue, No Resolution Yet

[SuzukiChopper]

I rebuilt my boat almost 3 years ago. New stringer, added ribs, new floor, foam, transom, did some customization, added a 19 gallon gas tank to the front, etc, etc, etc, etc. I love my boat. It's a 16' Delray (at least that's what the nice tag says on the side) and it has a '72 Johnson 100hp motor on it. I put a lot into the motor to make sure I'd get more years of service from it and even modified a 1986 Johnson power T&T for it so I didn't have to break my back at the dock and could adjust my plane depending on lake conditions. The boat is a little over powered but handles VERY nice (just need hydraulic assist steering). At WOT with 2 people in it I can hit about 55mph on a calm lake, with three people about 48mph. Both those figures with a full tank of gas up front and trimmed accordingly.

NOW, I've never been out with 4 people, just 2 or 3 (myself included) but I tried with 5 people. I'm about 200lbs, GF is about 130lbs, Dad is about 190lbs, Mom about 150lbs and my little sis was about 100lbs. My mom and dad and little sis in the back, me and my GF and a full 19 gallon tank of gas (and anchor) up front. I could NEVER get the boat to plane out. The motor would bog if I tried for WOT and I really had to ease in on it but the front end stayed up and I pretty much had to sit on my seat back to see over the front. Top speed was maybe 20mph. Not exactly sure of what prop I have on it but it's a 4 blade and I think 17" or 23" in diameter (????).

Do you not think I should be able to plane out at least and get up to some kind of nice cruising speed? The boat itself with me out of it never looked close to being weighed down and the motor is a little more motor then it should have, so I'm wondering if a different prop for those occasions would help or maybe smart tabs instead? I would like some opinions (or questions if need be to clarify things) so that I can take my family out once or twice this year. Thanks a bunch!

 

[tmcalavy]

Re: Old Issue, No Resolution Yet

Do a search for "prop pitch" and then consider changing the prop to another configuration. With that much extra load, it may need a different set of teeth to perform the way you want.

 

[tashasdaddy]

Re: Old Issue, No Resolution Yet

pull the prop of one the hub the size should be stamped. sound like you are pitched so high the motor can't get the load up. trimmed all the way in on take off should put that boat on plane immediately. also check the compression on the engine.

 

[Chris1956]

Re: Old Issue, No Resolution Yet

Sometimes Outboards will perform nicely with 4 people and not even plane with 5. It sounds like what happened to you. That means that you are optimally (or a bit over) propped. The cure is to drop the pitch of the prop 2". 50MPH out of a 100HP Johnny is quite an achievement, especially on a non-high performance hull.

 

[QC]

Re: Old Issue, No Resolution Yet

50MPH out of a 100HP Johnny is quite an achievement, especially on a non-high performance hull.

I agree, so frankly I am gonna assume the engine is running right. You need to post your RPM at WOT over on the prop forum. Bigger loads require lower pitch. If you work to prop this thing at the very top of your WOT RPM range with a light load, you may be OK with heavier loads without changing props. If not, you may have to change props depending on who and what your plan is for that day . . .

Any type of trim tab will definitely help. Smart Tabs or helm adjustables like Bennett's.

 

[tommays]

Re: Old Issue, No Resolution Yet

With my 19' 3.0 (135 HP) sterndrive a 14 X 21 prop works great with 2 to 3 people with NO need for trim tabs as long as there are no giant people in sitting in the two stern seats


If i put its max of 6 people it requires a 14 X 17 prop and TRIM TABS to get up on plane IF you want everybody to be able to stay in there seats

It is a common problem on low powered boats


Tommays

 

[SuzukiChopper]

Re: Old Issue, No Resolution Yet

Thanks for the feedback everyone!

I'll grab the numbers off the prop tonight and see what size it is for sure. I kind of figured it might be that but because it takes off like a bat outta hell with three people in there I found it kind of odd it would do that with 2 others but 350 extra lbs is quite a bit more to push.

Also, because my only boating experience so far has only been with 14' tinnies with 15hp motors and this boat, what I'm thinking is good right now probably isn't optimal for what the boat can do. I will tell you that dropping a few mph wouldn't hurt me at all if a different prop will get me to the WOT rpm numbers I should be seeing and if it will give me a more versatile boat.

I'll do some reading tonight about prop dynamics and such and post any questions I have in the prop section (if I can ever get out of the SHT jail ). Thanks again for the input!

 

[SuzukiChopper]

Re: Old Issue, No Resolution Yet

One other thing, I spent a LOT of time and some dollars to get that motor running like a top. Used to have troubles starting it and it dying at idle, but now even before it warms up, it fires right up all the time and will run all day (again thanks to the people on this forum that helped me out 3 years ago )

 

[Tail_Gunner]

Re: Old Issue, No Resolution Yet

I agree, so frankly I am gonna assume the engine is running right. You need to post your RPM at WOT over on the prop forum. Bigger loads require lower pitch. If you work to prop this thing at the very top of your WOT RPM range with a light load, you may be OK with heavier loads without changing props. If not, you may have to change props depending on who and what your plan is for that day . . .

Any type of trim tab will definitely help. Smart Tabs or helm adjustables like Bennett's.

Smart tab's will get tht old beauty out of the hole and enogh dough left over for a nice new shiny ss prop if you wish....

 

[SuzukiChopper]

Re: Old Issue, No Resolution Yet

Smart tabs are definitely on my list of things to buy for next year! Anyone have a used set they want to sell?