Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciated

[starcrazy]

and

Question is this, sprayed in low density foam or rigid pink insulation?

Here is the situation in point form, sort of long, but the question still remains the same.

-Rebuilding 1978 Strarcraft Mariner 18'

-Went to a boat show, showed pics of the boat and explained my plains to several salesman. I figured with a new motor I would spend more time of the water and have less hassles. So I purchased NEW 115 Etec.

-I've talked to the shop over the summer, again discussing my plans for boat in order to have it ready to mount the motor. One of his concerns was specifically the floatation, so I explained how I was going to accomodate it by using the rigid insulation, the pink kind.

So I am at the point to re-install the floatation, so I go to get a measuremnt for the steering cable so I can install it prior to installing the floatation and the floor. I figured that he can install the motor after I have finished installing the floor.

At this point he asks how I was going to deal with the floatation issue, I repeated the fact that I was going to use the rigid insulation, the pink kind. At this point he proceeds to tell me I CAN'T use rigid insulation , I ask why he said that I need to use the low density foam because I've increased the size of the motor and it has more torque then the previous motor (80 horse mercury). The low dense foam with stregthen the bottom of the hull more and the pink stuff will just constantly make noice. He also continues to say that I will pop out more rivets because of all the torque the new motor has.

So besides the fact that I am totally mad at the guy directing me in the direction of the motor, I am not sure which way to go. Sprayed in low density closed foam or the rigid insulation (pink).

Any thoughts would be greatly appreciated.:facepalm:

Thanks in advance

Regards

Wayne

 

[robert graham]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

Well, my thoughts would be that the spray-in foam would be difficult to remove for future repairs, modifications, rivet replacement, etc....while the rigid type you might cut it and slide it out fairly easily. Now I don't doubt that the spray-in type could have a structural/strengthening and sound dampening effect, but I wouldn't want it in my boat. Heck, I've heard of folks using lots of those closed-cell foam Pool Noodles under deck for flotation, easy to cut, install, and water would drain well through and around them...

 

[Pmccraney]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

Wow... Nice motor!!! This horse is getting a brand new saddle...

I am by no means an expert, but I have watched a lot of folks rebuild (and then run) metal boats with the pink (or blue) foam board... I just used the blue in mine. Some of these guys have re-powered within the limits of their boat... I am yet to hear of one that fell apart due to the torque of the motor. As long as your h/p is within limits of the boat, I can't imagine your boat ripping apart on you due to the torque of a newer engine.... I would imagine that if you have a nice, new strong transom (with a firmly installed knee brace) that those mechanisms would absorb the majority of your torque (oh, and maybe don't gun it out of the hole shot)...

If you are really worried, you can go with the 2-part (closed cell) pour-in foam, but just take care to make sure that you have adequate drainage back to the bilge....

 

[jasoutside]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

Wow, I think your shop guy is way off.

Wow, I think you have picked out a totally awesome engine!!

 

[GA_Boater]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

SC - what was originally under the floor? And what id the boat rated for power?

My thoughts on this, as long as the max power isn't exceeded the flotation won't make any difference. The torque referred to by the dealer is on the transom and knee braces. I don't see how the foam enters the picture. Now filling the hull with pour-in foam can affect the hull flexing, but it has absolutely nothing to do with the power on the back. With a center console pour-in foam might help minimize flexing if the boat is primarily used in rough water. Hopefully some of the tin CC folks will weigh in.

BTW - Nice choice for power!

 

[jigngrub]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

Spray foam can be used, but it has 2 drawbacks:
1. It's very expensive for the amount you get out of a can... it's actually the most expensive way to go out of all the foam options.
2. Spray foam has to be painted to be waterproof.

You can get the expanding 2 part urethane foam, the same stuff boat manufacturers are using here:
http://www.uscomposites.com/foam.html
... it is also expensive, but cheaper than the canned stuff.

There rigid sheet foam insulation is the best bang for the buck and is readily available almost everywhere. It has the same amount of floatation value as the 2 part expanding urethane foam but is considerably cheaper and esaier to work with.

 

[starcrazy]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

Thanks guys

Rob

I agree, I rather not have the spray in foam in there as well.

Craney

Yes the horse got a new saddle, lol . I have replaced the transom as well as all the rivits to the knee brace. Although the boat is 34 yrs old, the plate on the boat allows up to a 120 hp. Therefore I am within the recomended limit.

Jay

Hard to argue with a guy who does this for a living, but still not sure. The motor should do in a pinch, lol

Boater

The old white starfoam was under the floor previously. It was sooked for most of the hull. Maybe that is what he is concerned about, the flexing of the hull itself. The transom was rotten, and the rivets for the knee brace were still in place but were very loose. Therefore I replaced them as mentioned earlier.

His words were "it's going to be a rocket with that motor".

Grub

I am aware how expensive the foam stuff is, and way I wanted to stay away from it. I have already purchased most of the pink rigid insulation, another reason why I am so PO about it.

All in all, I just want to built the boat so it will last. This should be a one time thing for me if it is all done properly, which is what I am trying to do.

Thanks for you input guys, if anyone has any other comments, feel free to add your 2 cents.

Wayne

 

[jigngrub]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

To tell you the truth SC, I'm a huge fan of the 2 part expanding urethane foam.

The majority of people have some misconceptions about the expanding foam and/or want to save money.

The expanding foam is the best because it adheres itself to the hull and stays in place without depending on the decking to hold it down if the boat should fill with water.

A lot of people think the expanding foam is like a sponge and sucks up water as soon as it touches it, it doesn't. It takes an extended period of constant exposure to saturate the expanding foam.

This is the factory installed expanding foam in my '97 Tracker:

It is bone dry, and the way it was installed allows for proper drainage of the bilge.

I've forgotten to put the bilge plug in my boat a few times before launching and my boat floats like this:
http://www.youtube.com/watch?v=M30nDtZ4iys
When I take my boat out of the water after fishing all day with the plug out water shoots out of the bilge drain like a fire hose and I feel pretty dumb for forgetting the plug, but my boat doesn't sink and water never comes up through the deck drain.

 

[jigngrub]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

An important fact to remember about doing an expanding foam job at this time of year it temperature.

From the USComposite site:

All expansion rates and times given are temperature critical. Temperatures below 75 degrees F will lower the expansion rate therefore requiring more foam. Ideal working temperature is 75 to 80 degrees F or above.

 

[Georgesalmon]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

The two part polyurethane foam will help keep the aluminum hull from flexing. The polystyrene foam boards will not. The two part polyurethane foam will fill a lot more of the hull than the boards will. This will equate to more flotation in the boat. The amount of foam required to float the boat in an emergency is critical. IMHO if there is not enough flotation to keep the boat afloat in an emergency you might as well save some money and not use any at all. Use two part foam and use as much as was there originally.

I recall from my manufacturing experience that according to our bills of material some of our smaller models had more material cost in the flotation foam than we had in the aluminum.

 

[starcrazy]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

George

Thanks for making me feel so much better that it will cost more for the foam than I paid for the boat, lmao..

Looking into prices for the 2 part.

starcrazy

 

[jigngrub]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

George

Thanks for making me feel so much better that it will cost more for the foam than I paid for the boat, lmao..

Looking into prices for the 2 part.

starcrazy

Let us know if you find any place cheaper than the USComposites site, I haven't been able to find any place cheaper.

 

[starcrazy]

Re: Insulation question - Rigid or spray foam? Starcraft Mariner- Answers appreciate

I will

 

[Jet Mech 71]

I have an 08 Starcraft Islander with wet expanding 2 part foam. It is now removed and I am planning on putting the pink ridge foam in as a replacement. When my boat was built they did not put any drainage for water to get to the bilge. My port side foam once removed was around 200 lbs. After seeing there was no where for water to drain except one place near the transom. I feel if Starcraft had taken the time to put proper channels to get the water to the bilge my foam would not have absorbed all that water over the years. Expanding foam is good, but I just can't see manufacturer building a boat that will fall apart due to not having foam. My boat is just under 25ft long so per USCG it is not even required. It has taken me weeks to get all this expanding foam out of my hull and it is a pain!