Could I have soaked foam?

[Cariboo Milkman]

I have a 69 Merc 650 on a 14.5' fibreglass runabout of likely the same age. I have been trying to figure out why it takes forever or never to get the boat to plane and it has been suggested that maybe the foam is soaked. I scaled it today on the trailer, which I estimate is no more that 250-300 lbs, and the combo is about 1350 lbs. There might have been 50 lbs. of gear or so in the boat. Does it sound like it is possible the foam is soaked, or can I rule that out as a possible reason?
Thanks for any help.

 

[ricohman]

Re: Could I have soaked foam?

Lots of variables here. How strong does the engine seem? I'd start with that first.
Correct prop?

 

[Cariboo Milkman]

Re: Could I have soaked foam?

I've done, checked most of the engine related things-compression, carbs, plugs, timing, etc. to little avail. Repropped from 17" to 15". When it gets to plane, it runs to about 27 mph but has a lot of trouble getting through the middle rpms. I'm just trying to figure out if it could be soaked foam, because if so, I'm giving up on the boat as it's not worth the work to replace it.

 

[smokeonthewater]

Re: Could I have soaked foam?

weight looks about right to me

 

[crabby captain john]

Re: Could I have soaked foam?

Boat weight sounds about right. Trouble through the middle rpms? Fuel starvation.

 

[Watermann]

Re: Could I have soaked foam?

Not sure that a 69 would have the pour in foam that would water log. You could always drill some holes to check.

Have you done a compression check on the motor? RPMs at WOT?

 

[Home Cookin']

Re: Could I have soaked foam?

how does it look sitting still?

 

[chriscraft254]

Re: Could I have soaked foam?

What kind of boat? Make? model?

 

[Chris1956]

Re: Could I have soaked foam?

Gee, that 650 should be around 220#, with a 300# boat, it should plane easily with up to 4 adults. Weighing the combo would tell the tale. Remove all gear and excess weight, before weighing it. Second choice is to remove the motor and see if you and a friend can lift the boat. You should be able to after a fashion. if she is dead heavy and you cannot budge her, she has some extra weight in her.

 

[smokeonthewater]

Re: Could I have soaked foam?

he said in the first post that he weighed the boat motor and trailer and gear and it was 1350 lbs

300 lbs sounds light to me for a 14' glass boat... my 20' CC it right at 1000 and I'd expect a 14'er to be 500 lbs or more

 

[metriccrescentwrench]

Re: Could I have soaked foam?

.... a 14'er to be 500 lbs or more

Yep, that sounds ballpark at least. I had a 15 ft (actually 14 1/2 but it was called 15) and the hull weight for that was listed as 725 pounds. Also, I'm thinking Milkman might be a little light on his estimate of trailer weight.

HOWEVER, it doesn't sound like his boat weight is horribly out of whack. So as someone else suggested, start doing some basic diagnostics on the engine. Check compression on all cylinders. Do a drop test (pull plug wire off spark plugs one at a time while idling to see if engine rpm drops about the same amount for each), check spark with a spark tester (should jump about a 7/16" gap), see what the plugs look like (are any plugs obviously different than the others).

 

[Chris1956]

Re: Could I have soaked foam?

OK, Trailer is likely 150# or less, boat is likely 300#, motor 220# or less. So add that to 50# of gear, gives 670#. So you have about 700# of water..... All these are estimates, but based upon experience. Time to check it out closer.

 

[Chris1956]

Re: Could I have soaked foam?

Bubba, I had a 14 footer with a 35HP, and then a 50HP, all from the early 60s. You could plane that boat with either motor, with 600# of persons on board. It should leap out of the water with a 650, if the motor is running on all cylinders, and has good, even compression.

Heck in the 70s, the Jolly Rodger water ski boat ran a 650.

 

[Cariboo Milkman]

Re: Could I have soaked foam?

Thanks all for your suggestions. It seems the consensus is that the problem is less likely with the hull than with the engine. I will begin by rechecking compression (was 118-127 between all 4 when I got the boat a couple years ago) and see what I can find out about the spark strength. Hopefully I can discover something with some basic diagnostics. Boat is out of the water for the winter, so I have some time.

 

[Chris1956]

Re: Could I have soaked foam?

OK, if the motor checks out, take the motor off and try to life the boat. A friend and you should be able to lift it a bit. If you cannot budge it, it is waterlogged.

 

[limitout]

Re: Could I have soaked foam?

Not sure that a 69 would have the pour in foam that would water log.

you are correct, back in 69 they used trapped air pockets for floatation not foam (had several brands of them and replaced the floors in all but one) so unless the floor of the boat has been replaced and foam added it didn't come from the factory with anything but air under the floor.

those old boats are heavy, I can tell you that lol. I think you need to look into a motor or prop issue.

what is the history you know about the boat? have you owned it with it running and planning fine or is the boat new to you and you are trying to solve this issue?

 

[Chris1956]

Re: Could I have soaked foam?

Limit, My friend and his father would put their 1967 16' Winner up on saw horses (inverted, motor off), rather than cover it. My '60 Crestliner was balsa core (rotted of course).

 

[Cariboo Milkman]

Re: Could I have soaked foam?

I'm just assuming the boat is likely the same age as the motor. The only marking I have been able to find on it is a badge on either side of the stern that says "Marlin Plastics North Surrey BC". I picked up a spark tester today, and I'm going to check compression and spark and maybe a couple other things tomorrow.

 

[Cariboo Milkman]

Re: Could I have soaked foam?

I have had the boat for 2 seasons and have been trying to solve this since I got it. I have no idea of any history prior to that.