cannot keep bow down on grumman

[keuka10]

I have a 14ft grumman with a 9.9 merc. it planes off fine but any little ripple gets the bow bouncing up and down. i only have a 5 gallon tank in the middle and myself in the back.(165lbs) i checked the operating angle of the outboard and that seems correct. is it ok to weight down the bow with sand bags. thank you for any help.

 

[Bondo]

Re: cannot keep bow down on grumman

Either That,... Or a Longer Hose for the Fuel Tank......<br /><br />Maybe a Large Friend,....... They'll even Block the Spray for ya..............

 

[paulie0735]

Re: cannot keep bow down on grumman

Do a search for 'smart tabs' you will find all the answers there. Welcome to iboats.

 

[Silvertip]

Re: cannot keep bow down on grumman

This is a common problem on small tin boats. Get some weight up front and make sure the engine is not mounted so low that it acts as a lever to pop the bow up under power.

 

[keuka10]

Re: cannot keep bow down on grumman

thank you for the reply's. upinsmoke...i am not sure what you mean by mounted so low. there is not much room in regards to mounting. there are 3 points to adjust the trim. my understanding is the engeine closer to the hull keeps the bow and speed down.

 

[tashasdaddy]

Re: cannot keep bow down on grumman

the bottom of the boat should be in line with the cav. plate on the engine. i put and EzyGuide stick steering and remote shifter on my 14" lonestar w 15hp '55 rude. i drive from the middle seat, battery under front seat, gas in stearn, doing this made operating the boat a real pleasure, you can move around with out steping over a gas can, etc.

 

[Bondo]

Re: cannot keep bow down on grumman

Originally posted by keuka10:<br /> thank you for the reply's. upinsmoke...i am not sure what you mean by mounted so low. there is not much room in regards to mounting. there are 3 points to adjust the trim. my understanding is the engeine closer to the hull keeps the bow and speed down.

So,.......... Where is it Set Now,..???....

 

[cobra 3.0]

Re: cannot keep bow down on grumman

You can also try a hydrofoil. You will still need to mount the engine's cavitation plate in line with the bottom of the boat by simply inserting spacers between the engine mounts and the rim of the transom of the boat(bringing the motor up). This way the foil will be in line with the bottom of the boat and not create any drag in the water that may otherwise slow you down with the foil. <br /><br />You will also feel more stable in turns with the foil because the boat will hardly lean in turns.<br /><br />We had done this on our 14 ft aluminum boat and it felt much safer with one person and gave us a little more top end.

 

[Texasmark]

Re: cannot keep bow down on grumman

Or, put a couple of solid concrete blocks in the front (bow) to hold her down. That'll cost you about $10 and take 5 minutes. Typical problem with tiller handle operated boats.<br /><br />Mark

 

[Jdeagro]

Re: cannot keep bow down on grumman

The problem with putting permanent weight in the fron of the boat is that it may be good one time and not the next as the load or water conditions change. For example the forward mounted gas tank may be full or empty. The hydrofoil may or may not lift the stern too much at cruising speeds. If it creates too much lift the boat will run slower (because the bow is down too much) in addition to bow steering. <br /><br />We make Smart Tabs #ST780-20 for this application. These are active Trim Tabs which will significantly change the overall performance and handling of the boat including the porpoising that you are now experiencing.

 

[John_S]

Re: cannot keep bow down on grumman

Keuka, go out to the lake this weekend, it is suppose to be a nice weekend. Hopefully, not too windy. Try one position in, on your trim, closer to transom. See what that gets you. I adjust my trim, on my 14' boats, based on the people load. One rod position in, from perpendicular, is common for me with light loads. If you are going to put weight in the front, extend the gasline, and use the weight, already onboard. If the "free" changes don't get you there, then look at the smart tabs. <br /><br />If this is open style boat, without a floor, I would not recommend a weight like concrete blocks in the front. A solid weight bouncing up and down, will fatigue the aluminum. I've seen it from anchors, which didn't have the sharp edges of the blocks.

 

[b.gagnon]

Re: cannot keep bow down on grumman

what is the trim setting at?

 

[keuka10]

Re: cannot keep bow down on grumman

it is set at 1(closest to the stern) i put the gas tank up front, and will go out this weekend and play with the 3 settings.

 

[Texasmark]

Re: cannot keep bow down on grumman

Well then take a piece of carpet or other cushioning agent to put the tank on as I agree on the pounding not being good for the aluminum.<br /><br />Mark

 

[Matt3923]

Re: cannot keep bow down on grumman

Hi,

Had the same problem with my Grumman 15' Sportboat, its easy to fix. The most simple way is to remove the wood from where the motor mounts ans replace them with angled pieces. Quality cedar shingle works perfect for this, its cheap and waterproof. This changes the angle of the motor, you can always tilt it back up. Moving the gas tank to the front doesnt hurt either, just a pain to set up. Try the cheap lumber first, worked perfect for me and it raises the back of the boat.

 

[Texasmark]

Re: cannot keep bow down on grumman

The problem with putting permanent weight in the fron of the boat is that it may be good one time and not the next as the load or water conditions change. For example the forward mounted gas tank may be full or empty. The hydrofoil may or may not lift the stern too much at cruising speeds. If it creates too much lift the boat will run slower (because the bow is down too much) in addition to bow steering. <br /><br />We make Smart Tabs #ST780-20 for this application. These are active Trim Tabs which will significantly change the overall performance and handling of the boat including the porpoising that you are now experiencing.

Smart tabs on a 14' boat? Course if you can get into them for $100 then maybe it's not such a wild idea. He probably didn't pay $500 for the boat.

Mark

 

[NYBo]

Re: cannot keep bow down on grumman