Laser 13'6 still porpoises... bad

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
deltaninesix
Southern Airboat Member
Posts: 7
Joined: Thu Sep 15, 2011 12:18 am

Laser 13'6 still porpoises... bad

Post by deltaninesix »

I have a 13'6 Laser with SBC 305. I also have an electric trim tab and my boat will slam the fillings out of your teeth. It porpoises so bad! Its a single rear driver with double front passenger. It seems though, that when I have people in the front and its not just me it rides better and doesn't porpoise as much... but it still does. I moved the gas tank all the forward and that didnt even help all that much. Do you guys think I have something wrong with my hull or is it just a balancing issue? I want to add a grass rake so that would add some weight to the front. I also looked at the angle of the motor while it floats... it is down a little bit in the back already which is one fix Ive heard. How much of an angle for a 13'6 boat is okay?
Attachments
IMG_1291.JPG
IMG_1291.JPG (100.49 KiB) Viewed 2347 times
299315_582884572779_29802464_32510382_4009233_n.jpg
299315_582884572779_29802464_32510382_4009233_n.jpg (24.47 KiB) Viewed 2347 times

User avatar
BANANA BOAT
Site Supporter - I
Site Supporter - I
Posts: 1161
Joined: Tue Sep 21, 2010 3:52 pm

Re: Laser 13'6 still porpoises... bad

Post by BANANA BOAT »

That boat need's screw jack's put in.They push the stringer's down,under the engine.inexpensiveI know the boat.We tried changing engine angle,That did not help.

User avatar
CJB0470
Site Supporter - III
Site Supporter - III
Posts: 1218
Joined: Sun Jan 04, 2009 9:10 am
Location: Port St Lucie

Re: Laser 13'6 still porpoises... bad

Post by CJB0470 »

My 13.6 Cottonmouth porpoised when I bought it. I jumped a levy and broke the trim tab and bounced all the way back to the trailer. In 2005 I bought a new hull and adjusted the angle on the motor until it stopped. See if you can adjust the engine angle, if not use the screw jack to push the bottom down. Take it out and make small adjustments and see how it responds.
Chris.
"Always do right. This will gratify some people, and astonish the rest"
-Mark Twain

User avatar
Whitebear
Site Supporter - VIII
Site Supporter - VIII
Posts: 16555
Joined: Thu Jan 05, 2006 7:49 pm
Location: Palm Bay, Fl
Contact:

Re: Laser 13'6 still porpoises... bad

Post by Whitebear »

You mentioned it has a trim tab but you didn't say if the trim tab will stop the porpoising or not?

Its always a balancing problem and its always fixable.

Put a straight edge on those stringers to start with and see what ya have.
"The Constitution is not so the government can restrain the people, it is so the people can restrain the government." Patrick Henry
The government cannot give anything --
that they have not first taken from someone else.

User avatar
BANANA BOAT
Site Supporter - I
Site Supporter - I
Posts: 1161
Joined: Tue Sep 21, 2010 3:52 pm

Re: Laser 13'6 still porpoises... bad

Post by BANANA BOAT »

We tried adjusting engine angle.No help. Screw jacks.Trim tab helped when we had the boat.

User avatar
AirRanger
Site Supporter - I
Site Supporter - I
Posts: 1192
Joined: Thu Nov 30, 2006 9:23 pm
Location: Gibsonton,Fl
Contact:

Re: Laser 13'6 still porpoises... bad

Post by AirRanger »

The fuel tank seems very far forward. Could it be that you have plenty of power to lift that heavy fuel tank above plane then the weight of it just keeps pushing the nose back down?
Image

mrfixit
Southern Airboat Member
Posts: 190
Joined: Sat Aug 06, 2011 10:21 pm
Location: Dunnellon, FL

Re: Laser 13'6 still porpoises... bad

Post by mrfixit »

The fuel tank location is fine to help with the porpas issue . lower the back of the engine mite help. put the boat on a trailer level the bottom of the boat find a machened surface that is flat on the engine check it for level and make it so to start with from there I would try lowering no more then 3/8 of an inch. I t would be a good idea fi problem exist to check the botom for high spot or hook.

cowtown
Site Supporter - III
Site Supporter - III
Posts: 1558
Joined: Fri Aug 08, 2008 7:29 pm
Location: Fellsmere,Florida
Contact:

Re: Laser 13'6 still porpoises... bad

Post by cowtown »

sounds like the hull has a hook in it , multiple jacks may be required to hold the hulls shape , just a thaught.
http://usfth.tripod.com

And Proud Of It !!!

deltaninesix
Southern Airboat Member
Posts: 7
Joined: Thu Sep 15, 2011 12:18 am

Re: Laser 13'6 still porpoises... bad

Post by deltaninesix »

Okay thanks guys. Like bananaboat said, trim tab helps a lot compared to no trim tab but it's still bad. As for the screw jacks...

They go lengthwise down the center along with the stringers correct? And how long do I need them to be? And one more question, how far from the transom should they start?

Thx again guys!

User avatar
AirRanger
Site Supporter - I
Site Supporter - I
Posts: 1192
Joined: Thu Nov 30, 2006 9:23 pm
Location: Gibsonton,Fl
Contact:

Re: Laser 13'6 still porpoises... bad

Post by AirRanger »

The jacks don't go lengthwise, they go across (adjacent to) the stringers. Some boats have two and some have three.
Image

Striker543
Site Supporter - I
Site Supporter - I
Posts: 1035
Joined: Wed Oct 13, 2010 11:03 pm
Location: Miami/Orlando, Fl

Re: Laser 13'6 still porpoises... bad

Post by Striker543 »

My old hull was the same way. 12.5 ft hull with a 350 DD and it would buck you out of the boat it was so bad. Even with the gas tank all the way up, toolbox in the bow, and two people riding on the bow, it still bounced like hell. The bottom also was awful - it was "re-glassed" by someone who did not know what they were doing and it resulted in lots of "pits" and an overall uneven surface.

Bought a new hull - exact same engine, prop, and rigging (except the gas tank moved back) - and it rides like a dream. Depending on the age and condition of your hull, it may be an option. You can pick up used glass hulls in "like new" condition for pretty cheap if you wait for the right deal.

mrfixit
Southern Airboat Member
Posts: 190
Joined: Sat Aug 06, 2011 10:21 pm
Location: Dunnellon, FL

Re: Laser 13'6 still porpoises... bad

Post by mrfixit »

You mite want to pull the rigging off the hull flip the hull over and check it with a long straight edge. if bad it could be repared.
Oh by the way is there poly on this boat. have seen poly installed bad cause all kind of problems.

Nozzle Head

Re: Laser 13'6 still porpoises... bad

Post by Nozzle Head »

This should help in what you don't want to find.
You can check it with scuba gear too if you don't want to pull the rigging? A straight stick of emt works if you don't have a t square?
Attachments
2IMG_0691.jpg
2IMG_0691.jpg (187.65 KiB) Viewed 2061 times

deltaninesix
Southern Airboat Member
Posts: 7
Joined: Thu Sep 15, 2011 12:18 am

Re: Laser 13'6 still porpoises... bad

Post by deltaninesix »

Okay, I just had a look. And even on the trailer I can tell the hull is "wonkey." It looks about as bad as the pic above. How can this be fixed, adding poly? Or does the bottom need to be re-glassed? I like the set up of the boat now so if I can get this one fixed for less than buying a new hull I would prefer to do that.

Nozzle Head

Re: Laser 13'6 still porpoises... bad

Post by Nozzle Head »

Lift the rigging and reglass, you may want to check your stringers especially around the bilge weep holes too.

Striker543
Site Supporter - I
Site Supporter - I
Posts: 1035
Joined: Wed Oct 13, 2010 11:03 pm
Location: Miami/Orlando, Fl

Re: Laser 13'6 still porpoises... bad

Post by Striker543 »

Unless you're good with glass, I wouldn't recommend trying to do it yourself - it's not easy to get it perfectly straight. Even if you hire a professional, by the time you pay them, you could probably be halfway to buying a new hull. You may be better off saving up to get another hull, used or new, as long as the used hull has a good bottom.

Now, I know very little about polymer, but putting polymer on may hide your hull issues. Some of those experienced with polymer will have to chime in.

cowtown
Site Supporter - III
Site Supporter - III
Posts: 1558
Joined: Fri Aug 08, 2008 7:29 pm
Location: Fellsmere,Florida
Contact:

Re: Laser 13'6 still porpoises... bad

Post by cowtown »

why not build it up with steelflex2000, or other brand , and install a new sheet of poly if you decide to run poly, just a thaught!
http://usfth.tripod.com

And Proud Of It !!!

deltaninesix
Southern Airboat Member
Posts: 7
Joined: Thu Sep 15, 2011 12:18 am

Re: Laser 13'6 still porpoises... bad

Post by deltaninesix »

That's kind of what I have been thinking of getting done. Fill the wonky glass with some sort of filler to get it smooth and give the polymer a flat base to start with. The polymer would hide any small imperfections and give me a decent bottom to start with.

User avatar
BANANA BOAT
Site Supporter - I
Site Supporter - I
Posts: 1161
Joined: Tue Sep 21, 2010 3:52 pm

Re: Laser 13'6 still porpoises... bad

Post by BANANA BOAT »

That was a new slick bottom when you got the boat.Cowtown has it right,screw jack's so the stringer's do not move.(bottom hold shape). hook in bottom near stern.other than that,the boat run's like a top

tkendall82
Southern Airboat Member
Posts: 87
Joined: Sat Oct 17, 2009 10:23 pm

Re: Laser 13'6 still porpoises... bad

Post by tkendall82 »

Fill the low spots with Duraglas, then put a fresh coat of steelflex on it whether you put poly on it or not. Jacks will hold the bottom true but the bottom has to be flat to start with.

dusty burch
Southern Airboat Member
Posts: 317
Joined: Sat Jul 09, 2011 3:09 pm
Location: gainesville ,fl
Contact:

Re: Laser 13'6 still porpoises... bad

Post by dusty burch »

:violent1: sounds like u just need a new hull if u put all the work in that old boat it will just come apart and u will be where u are right now also jacks wont help with a bottom that is that bad

User avatar
BANANA BOAT
Site Supporter - I
Site Supporter - I
Posts: 1161
Joined: Tue Sep 21, 2010 3:52 pm

Re: Laser 13'6 still porpoises... bad

Post by BANANA BOAT »

does not need new hull,I'll say it again jack's(inexpensive).If they do not work,then consider something different.

User avatar
bowhunterfl
Site Supporter - IV
Site Supporter - IV
Posts: 444
Joined: Fri Mar 04, 2011 9:56 am
Location: high spring

Re: Laser 13'6 still porpoises... bad

Post by bowhunterfl »

My little hull did the same thing I put jacks in and it fix it for a couple of rides and know the bottom is so war out even the jacks don't help.
And filling the low spots with slick bottom does not help the bottom still flex the same
14' combee 454 BBC 2to1 belt drive spinnen 3 wirlwind master blasters.

User avatar
BANANA BOAT
Site Supporter - I
Site Supporter - I
Posts: 1161
Joined: Tue Sep 21, 2010 3:52 pm

Re: Laser 13'6 still porpoises... bad

Post by BANANA BOAT »

We filled the whole bottom with steelflex.It level.Jack's will make the stringer's rigid.If jack's do not work, the next hull you get might need jack's.I have a mint condition laser that use's jack's to prevent porpoising.
Last edited by BANANA BOAT on Sat Oct 08, 2011 10:04 pm, edited 1 time in total.

dusty burch
Southern Airboat Member
Posts: 317
Joined: Sat Jul 09, 2011 3:09 pm
Location: gainesville ,fl
Contact:

Re: Laser 13'6 still porpoises... bad

Post by dusty burch »

BANANABOAT wrote:does not need new hull,I'll say it again jack's(inexpensive).If they do not work,then consider something different.
if the bottom looks that bad it is had it :cheers:

Post Reply

Return to “Airboat Tech”