deckboat plane problems please help

[dahcyarg]

I have a 1997 starcraft starship 2000 db deckboat and have problems getting it up on plane. have a 1997 force 120 hp engine with stock 3 blade prop with a few scratches on it. boat pulls well but I cant get it to plane out with more than one or two people in it(in which I have gotten it up to 25-30 mph). tried different tilt positions from all the way in to over 1/4 way out and same problem gps does not hit over 10 to 11 mph. I just ordered a hydrofoil to go on the motor to see if that will help do I need to replace the prop and if so what prop should I get? please help.

 

[Robbabob]

Re: deckboat plane problems please help

Hi and welcome to iboats!

You provided a lot of helpful information, but we still need a little more. Review this link and fill in the information again... .http://forums.iboats.com/showthread.php?t=287818

Mostly just need what rpm you are hitting, the pitch and material of current prop, etc.

Good luck!

 

[dahcyarg]

Re: deckboat plane problems please help

1) Performance issue you are trying to correct.
trying to get boat to plane out with friends aboard approx 300-400 lbs more with added weight top speed 13 mph wontget on plane tried having everyone sit in back and in front started with motor trimmed almost all the way in and played with trim a bunch. getting a bunch of splashing up front but wont finally get up on plane. also put a super screamer tube behind with 4 adults 1 kid (1 of adults on tube) and max speed was 12.5 mph. rope seems to drag in water a bunch since i only have transom mounts on either side of engine to attach to and they are only like a foot off the bottom of the boat.
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
-quicksilver aluminum qa2034x 13.75 dia 15 pitch swapped from a stock 17 pitch prop and added a se sport hydrofoil helped a bunch since was not able to plane before with just wife and kid unless in shallow water put se sport hydrofoil on and with stock prop took a bit to plane out but then got up to 30 mph then put 15 pitch prop on and got up in less than a minute and would do top 25 -27
3) Current prop diameter and pitch (required).
4) Wide open throttle RPM and speed with an average load (very helpful)
4800-4900 at 1/4 or so trim 25 mph max mostly 21 ave load 2 adults and 1 kid + gear approx 600 lbs max load 1700 lbs rated
rpm after i fixed the tach which was on the wrong pos now tracks great max motor rpm rated 5250
5) Engine/drive make, model, year, and HP
1997 force by merc 120 hp exlpt
6) Boat make model, year, length and weight
starcraft starship 2000 db 1997 20' weight rated 3000 lbs

 

[steelespike]

Re: deckboat plane problems please help

What is the boats max rated hp?The Force isn't known for its power or speed so if it had the slightest condition issue it would likely fade fast.I would think that a strong Force should run
over 30 on that boat. I'd start by proving the motor is healthy and properly tuned and timed.
I think that has multi carbs one or more could be messed up.

 

[dahcyarg]

Re: deckboat plane problems please help

rated for up to 150 hp is there an easy way to check the timing or carbs I'm pretty new to this stuff just ordered manual

 

[steelespike]

Re: deckboat plane problems please help

While the Foil can be a big help it is usually a bandaid over a setup problem.
Sorry I don't know the details on the Force.They do have the regular ignition timing and
all outboards have a link and sync ie: the carbs need to begin to open at the right time as the throttle advances.
You can look at each carb and be sure they are all opening together all the way.
Pull the plugs note their location and condition.they should look brownish to slightly black.
not wet or shiny black or super clean.Let us know what you find.While your at it check the compression.
Check the height of the motor.The antivent plate(just above the prop)should be about even with the bottom.Some motors end up about 1" above.
If the motor is too low you are dragging too much through the water also the foil will be under as well sapping some of your speed.

 

[dahcyarg]

Re: deckboat plane problems please help

Just got the shop manual for the motor so now going through tune-up on engine.
the foil and plate are just even with the bottom of the boat. the engine is at it's highest bolt holes. I replaced all 4 spark plugs and the old ones had normal deposits and some oil on the threads is this normal? bought timing light and compression gauge today and will check those in the next week. I was wondering about how to see that both carbs open fully as i don't seem to have the alan wrench to take off the intake cover (sort of confused about that).
I did find at with the engine off at full throttle position there was still a bit of play with the carb throttle so i tightened up the throttle link. got maybe 1/8" or so of play. Assumed that means that it was not truely at full throttle.