C17 in the bayou

[Eric1]

Should be the same primer. As for graphite, no need to prime.
Put it right over your glass.

[Salty F17]

Should be the same primer. As for graphite, no need to prime.
Put it right over your glass.

Great thanks love your build too lots of info

[TomW1]

Good stuff Salty!! Jeff

I was curious as what that max hp is for this boat I did the coast guard calculations and I would seem that it is 130hp this cant be right would you be able to answer this question ? For me

Salty the CG calculations are always about double or triple of what Jacques recommendations are. There are two basic reasons for this, first liability, if someone puts that much HP on one of his designs he doesn't want them to come back on him. Second the design parameters.he has designed the boat for the recommended HP plus a safety factor, adding to much more will require adding additional fiberglass in certain areas to support the extra HP, this adds extra cost which is not the reason he started the company, I believe. There is basically not a designer in the country building to the CG calculations because of these two reasons, liability and cost.

Now having said that I have propped a couple of C17's and a 50HP will give you a top speed in the mid 30's with a good SS prop. A C17 will gain about 3 mph for each 10HP added per her hull design and carrying the same weight. You could consider the new light weight 60 or 70 HP motors that are available from Yamaha, Suzuki and Mercury. This would be the absolute highest that you should go and for 6mph is it worth the cost.

Tom

[jacquesmm]

Thanks, Tom, that is correct.
Unless the builder builds the boat 100% as designed, I can not guarantee the specs. The boat never is 100% as designed. That is why, if there is a capacity tag, it must be made by the builder. I do those calculations for production boats, amateur-built boats do not require it.
Considering that I always include a motorwell bulkhead and in many cases, have a wide and high transom, the USCG capacity calculations often produce an exceedingly high max. HP and number of persons. For example, 20 years ago, the PH18 was in fiberglass production under the name Ghost and I did the calculations. We got about 250 HP and 11 persons which is ridiculous. Common sense tells even a beginner that it would be dangerous but the builder can be found liable if an accident happens as a result of excessive speed or overload. The tag showed 90. There is another point for max. HP that we rarely discuss, the driving test. The USCG rules specify that a boat must be able to run a specific slalom between buoys at max. speed, see section H26/7 of the ABYC rules, title "maneuvering Speed" and "Avoidance test". A PH18 with a 250 HP can't do that but it is possible with a 90 and a skeg. That USCG rule applies to speeds above 30 mph and I like to say that I design those boats for less than 30 mph even if they all go faster.
I guess that the calculations may very well produce 115 or more HP for the C17 but it will not be able to do the avoidance test with more than 90.
It does not mean the boat will break, it means that it not safe.

Production boat builders are faced with a dilemma: announce a high max. HP that is attractive to the buyer or a low one to cover their liability.

Then, there is the fact that production boats are much heavier. 20 years ago, we went to a local boat ramp to test a PH18 made from ply-epoxy with foam components: 575 lbs! We had a 70 on the transom. Next to us, at the ramp was a brand new Maverick prototype with a 125. We had a better holeshot and top speed than the production boat with a lot less HP.

PS: what we call USCG calculations are, in the case of powering, ABYC industry standards, not USCG.

We are working on a new website and I will add text to the study plans to explain that the max. HP is my opinion. I may list two values: max. HP per USCG calcs and "designers opinion".

[TomW1]

Jacques I don't know if I would bring in the USCG max if I were you. It is so high that it may confuse more builders that it will help. What you might do instead is bring in the max hp of the build as is and then what would happen if they added a layer of glass to the bottom and reinforced the corners of the transom as an option. I would be sure that these designs are designed for a maximum HP and anything over that makes them an experimental boat for which you as the designer can have no liability. Some guys just want to push the limit and will. Don't encourage them.

Tom

[Salty F17]

Jacques I don't know if I would bring in the USCG max if I were you. It is so high that it may confuse more builders that it will help. What you might do instead is bring in the max hp of the build as is and then what would happen if they added a layer of glass to the bottom and reinforced the corners of the transom as an option. I would be sure that these designs are designed for a maximum HP and anything over that makes them an experimental boat for which you as the designer can have no liability. Some guys just want to push the limit and will. Don't encourage them.

Tom

I would amen that that makes perfect sense

[Salty F17]

Thanks, Tom, that is correct.
Unless the builder builds the boat 100% as designed, I can not guarantee the specs. The boat never is 100% as designed. That is why, if there is a capacity tag, it must be made by the builder. I do those calculations for production boats, amateur-built boats do not require it.
Considering that I always include a motorwell bulkhead and in many cases, have a wide and high transom, the USCG capacity calculations often produce an exceedingly high max. HP and number of persons. For example, 20 years ago, the PH18 was in fiberglass production under the name Ghost and I did the calculations. We got about 250 HP and 11 persons which is ridiculous. Common sense tells even a beginner that it would be dangerous but the builder can be found liable if an accident happens as a result of excessive speed or overload. The tag showed 90. There is another point for max. HP that we rarely discuss, the driving test. The USCG rules specify that a boat must be able to run a specific slalom between buoys at max. speed, see section H26/7 of the ABYC rules, title "maneuvering Speed" and "Avoidance test". A PH18 with a 250 HP can't do that but it is possible with a 90 and a skeg. That USCG rule applies to speeds above 30 mph and I like to say that I design those boats for less than 30 mph even if they all go faster.
I guess that the calculations may very well produce 115 or more HP for the C17 but it will not be able to do the avoidance test with more than 90.
It does not mean the boat will break, it means that it not safe.

Production boat builders are faced with a dilemma: announce a high max. HP that is attractive to the buyer or a low one to cover their liability.

Then, there is the fact that production boats are much heavier. 20 years ago, we went to a local boat ramp to test a PH18 made from ply-epoxy with foam components: 575 lbs! We had a 70 on the transom. Next to us, at the ramp was a brand new Maverick prototype with a 125. We had a better holeshot and top speed than the production boat with a lot less HP.

PS: what we call USCG calculations are, in the case of powering, ABYC industry standards, not USCG.

We are working on a new website and I will add text to the study plans to explain that the max. HP is my opinion. I may list two values: max. HP per USCG calcs and "designers opinion".

I totally understand

[Rmarsh]

Hi Salty...I have a 60 hp Yamaha 4 stroke on my C17, it weighs about 240 lbs., at that weight the boat sits level in the water at its DWL. So keep in mind that a heavier engine may adversely affect the trim. Also...in five years of steady use......I have never once felt the need for more speed or power.
Bob

[Salty F17]

Can wait to get back started i order the the hull and transom wood so more drafting cutting and finally starting the glue and stitch process of the build also fter reviewing the oc17 and c17 plans I will be doing the oc panels on this build as they are the plans that wobblelegs and rmarsh used the plans seem to have switched the panels so I guess this is now the oc17 cc

[Salty F17]

Thanks, Tom, that is correct.
Unless the builder builds the boat 100% as designed, I can not guarantee the specs. The boat never is 100% as designed. That is why, if there is a capacity tag, it must be made by the builder. I do those calculations for production boats, amateur-built boats do not require it.
Considering that I always include a motorwell bulkhead and in many cases, have a wide and high transom, the USCG capacity calculations often produce an exceedingly high max. HP and number of persons. For example, 20 years ago, the PH18 was in fiberglass production under the name Ghost and I did the calculations. We got about 250 HP and 11 persons which is ridiculous. Common sense tells even a beginner that it would be dangerous but the builder can be found liable if an accident happens as a result of excessive speed or overload. The tag showed 90. There is another point for max. HP that we rarely discuss, the driving test. The USCG rules specify that a boat must be able to run a specific slalom between buoys at max. speed, see section H26/7 of the ABYC rules, title "maneuvering Speed" and "Avoidance test". A PH18 with a 250 HP can't do that but it is possible with a 90 and a skeg. That USCG rule applies to speeds above 30 mph and I like to say that I design those boats for less than 30 mph even if they all go faster.
I guess that the calculations may very well produce 115 or more HP for the C17 but it will not be able to do the avoidance test with more than 90.
It does not mean the boat will break, it means that it not safe.

Production boat builders are faced with a dilemma: announce a high max. HP that is attractive to the buyer or a low one to cover their liability.

Then, there is the fact that production boats are much heavier. 20 years ago, we went to a local boat ramp to test a PH18 made from ply-epoxy with foam components: 575 lbs! We had a 70 on the transom. Next to us, at the ramp was a brand new Maverick prototype with a 125. We had a better holeshot and top speed than the production boat with a lot less HP.

PS: what we call USCG calculations are, in the case of powering, ABYC industry standards, not USCG.

We are working on a new website and I will add text to the study plans to explain that the max. HP is my opinion. I may list two values: max. HP per USCG calcs and "designers opinion".

I have one more question? , is it ok to use 6566 for the bulkheads,sole and motorwell ?