„Pumpfoiling \u2013 Importance of the Body Position and Weight Distribution“<\/a>\u00a0 you can find a detailled explanation about the forces and moments acting when pumpfoiling. From there we know that the momentum theorem as well as sum of the forces is valid also for pumpfoiling.\u00a0So wat happens now if we add a shim?<\/p>\nBy inserting a shim between the fuselage and the backwing, we change the angle of attack of the backwing and with that the lift of the backwing. Due to the change of the force of the backwing, the resulting momentum along the pitch-axis is changed, which results in a different behaviour of the overall setup.<\/p>\n
[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/Momentum-Theorem.png“ title_text=“Momentum Theorem“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“76%“ width_tablet=“93%“ width_phone=“100%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Figure 7 – Momentum theorem with impact of changing backwing force<\/p>\n
[\/et_pb_text][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
When you look up shimming in the internet, you will sooner or later get confronted with the fact, that there are different ways how foiling setups are assembled. Although they look all similar, there are some specifics. What is relevant for us in the context of shimming the backwing is how or where the backwing is mounted on the fuselage. In some setups, the backwing is mounted on top of the fuselage, in some others underneath. Some setups also use a so called angle adaptor between the fuselage and the backwing.<\/p>\n
[\/et_pb_text][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Variant 1<\/strong><\/p>\n\n- Backwing attached on top of the fuselage<\/li>\n
- Backwing mounted using an angle adaptor<\/li>\n<\/ul>\n
[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=“1_2,1_2″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_column type=“1_2″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/1100P_cut2_small.png“ alt=“Indiana 1100P Foil“ title_text=“1100P_cut2_small“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“68%“ width_tablet=“54%“ width_phone=“54%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][\/et_pb_column][et_pb_column type=“1_2″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/BackwingOnTopFuselage_AngleAdaptor.png“ title_text=“BackwingOnTopFuselage_AngleAdaptor“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“100%“ width_tablet=“70%“ width_phone=“90%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_column type=“4_4″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Variant 2<\/strong><\/p>\n\n- Backwing attached underneath the fuselage<\/li>\n
- Backwing mounted using an angle adaptor<\/li>\n<\/ul>\n
[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=“1_2,1_2″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_column type=“1_2″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/1190_cut_small.png“ alt=“Indiana 1190″ title_text=“1190_cut_small“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“68%“ width_tablet=“54%“ width_phone=“54%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][\/et_pb_column][et_pb_column type=“1_2″ _builder_version=“4.14.1″ _module_preset=“default“ custom_padding=“20px||||false|false“ global_colors_info=“{}“][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/BackwingUnderneathFuselage_AngleAdaptor.png“ title_text=“BackwingUnderneathFuselage_AngleAdaptor“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“100%“ width_tablet=“70%“ width_phone=“90%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_column type=“4_4″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Variant 3<\/strong><\/p>\n\n- Backwing attached underneath the fuselage<\/li>\n
- Backwing mounted directly without angle adaptor to the fuselage<\/li>\n<\/ul>\n
[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=“1_2,1_2″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_column type=“1_2″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/1200_cut_small.png“ alt=“Indiana 1200 A-HR“ title_text=“1200_cut_small“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“68%“ width_tablet=“54%“ width_phone=“54%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][\/et_pb_column][et_pb_column type=“1_2″ _builder_version=“4.14.1″ _module_preset=“default“ custom_padding=“30px||||false|false“ custom_padding_tablet=“30px||||false|false“ custom_padding_phone=“30px||||false|false“ custom_padding_last_edited=“on|tablet“ global_colors_info=“{}“][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/BackwingUnderneathFuselage.png“ title_text=“BackwingUnderneathFuselage“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“100%“ width_tablet=“70%“ width_phone=“90%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_column type=“4_4″ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
When you apply a shim at your foil, you must pay attention how your setup is assembled so that you will get the suitable shim for your intended purpose. A shim is basically a wedge that you put in between the fuselage and wing. So you will have to remove the wing and place the shim in between.<\/p>\n
[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/Shim-Assembly.png“ title_text=“Shim Assembly“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“69%“ width_tablet=“73%“ width_phone=“89%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Figure 8 – Adding a shim in between the fuselage and backwing<\/p>\n
[\/et_pb_text][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Due to the shape of the shim \u2013 please note that there are positive and negative shims, we will look into that later \u2013 the angle in that the wing is mounted on the fuselage, will change. In this example, we are using a negative shim and you can see that the trailing edge of the wing is now pointing more upwards.<\/p>\n
[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/Change-in-angle-of-attack-with-shim.png“ title_text=“Change in angle of attack with shim“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“77%“ width_tablet=“77%“ width_phone=“100%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Figure 9 – In yellow position of the wing without shim, in black the position of the wing with a shim<\/p>\n
[\/et_pb_text][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
If we bring that now back into the formula of the forces and moments, we can see the effect of the shim. Having added the shim the angle of attack of the backwing has increased. That results in a bigger force generated by the backwing and with that also in a bigger momentum induced by the backwing. Due to that change in the momentum, the foiler will feel more lift in front of the board.<\/p>\n
[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/Change-in-Force-and-Momentum-Due-to-Shimming.png“ title_text=“Change in Force and Momentum Due to Shimming“ align=“center“ _builder_version=“4.14.1″ _module_preset=“default“ width=“74%“ width_tablet=“88%“ width_phone=“100%“ width_last_edited=“on|phone“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Figure 10 – Change in the momentum due to the change in the angle of attack of the backwing<\/p>\n
[\/et_pb_text][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
As we can see, adding a shim between the fuselage and backwing has an influence on the overall system.\u00a0Depending on in which direction you want to trim your setup, you can make use of negative of positive shims with different angles.<\/p>\n
[\/et_pb_text][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Impact of Negative and Positive Shims<\/h2>\n
To understand better how the shims are influencing the system, I put together a small overview that should help you to choose the correct shim.<\/p>\n
[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2023\/12\/Overview-Shimming-Directions-and-Effect.png“ title_text=“Overview Shimming Directions and Effect“ _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Table 1 – Overview negative and positive shims and their effects<\/p>\n
[\/et_pb_text][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
As mentioned earlier, the first thing we have to distinguish if the backwing is mounted underneath or on top of the fuselage so that you can identify if you need a positive or negative shim. If you want to move the trailing edge of the backwing higher, what will result in:\u00a0<\/p>\n
\n- More drag<\/li>\n
- More lift<\/li>\n
- More pitch stability<\/li>\n
- Less glide<\/li>\n
- Stiffer turning<\/li>\n<\/ul>\n
<\/ul>\n\u00a0you will have to choose a so called negative shim in case that the backwing is mounted underneath the fuselage and a so called positive shim in case the backwing is mounted on top of the fuselage.\u00a0<\/p>\n
In case you want to move the trailing edge down to have a flatter positioned backwing, which will result in\u00a0<\/p>\n
\n- Less drag<\/li>\n
- Less lift<\/li>\n
- Less stability<\/li>\n
- More glide<\/li>\n
- Looser feeling<\/li>\n<\/ul>\n
<\/ul>\n\u00a0you have to choose a positive shim in case the backwing is mounted underneath the fuselage and a negative shim in case the backwing is mounted on top of the fuselage.<\/p>\n
Please note that illustrations here are used to indicate the direction and are exaggerated. Not all setups have in the so called neutral position (without a shim) the same angle and therefore, the shim is always changing to a new angle from the position without a shim \u2013 which does not has to be zero.<\/p>\n
Earlier I also mentioned that some brands are using angle adaptors between the fuselage and the backwing. For sure, also for those setups you can work with shims, however many of the brands who designed the setup with an angle adaptor also offer angle adaptors with different angles of attack, so that you can just replace the angle adaptor with a different angle.<\/p>\n
[\/et_pb_text][et_pb_text _builder_version=“4.14.1″ _module_preset=“default“ global_colors_info=“{}“]<\/p>\n
Conclusions<\/h2>\n
By adding a shim, you are changing the angle of attack of the backwing and with that its lift force. With that you can influence the pitch moment of the foil, which is going along with impact on the glide, stablility and agility on the turns.<\/p>\n
Dependent on your setup, you have to be aware to choose the correct shim (either negative or positive) to achieve the desired result.<\/p>\n
[\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]<\/p>\n","protected":false},"excerpt":{"rendered":"
When you start with pumpfoiling, you will most probably just use the equipment that is provide either by the school where you take a lesson or in case you do the first attempts with your friends, just use their equipment. However, once you get more into pumpfoiling you will look more into the details of […]<\/p>\n","protected":false},"author":1,"featured_media":30190,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-30122","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/posts\/30122","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/comments?post=30122"}],"version-history":[{"count":42,"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/posts\/30122\/revisions"}],"predecessor-version":[{"id":30198,"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/posts\/30122\/revisions\/30198"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/media\/30190"}],"wp:attachment":[{"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/media?parent=30122"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/categories?post=30122"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pumpfoilers.ch\/en\/wp-json\/wp\/v2\/tags?post=30122"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}